Sample records for view graph graph

  1. Multiple Coordinated Views for Network Attack Graphs Steven Noel Michael Jacobs Pramod Kalapa Sushil Jajodia

    E-Print Network [OSTI]

    Noel, Steven

    Multiple Coordinated Views for Network Attack Graphs Steven Noel Michael Jacobs Pramod Kalapa graph-based representations have been developed for modeling combinations of low-level network attacks, relatively little attention has been paid to effective techniques for visualizing such attack graphs

  2. university-logo Graph Expansions

    E-Print Network [OSTI]

    St Andrews, University of

    university-logo Graph Expansions Green's Relations Closing Remarks Semigroup Graph Expansions January 2009 Rebecca Noonan Heale Semigroup Graph Expansions: #12;university-logo Graph Expansions Green;university-logo Graph Expansions Green's Relations Closing Remarks History Definitions Graph Expansions

  3. Drawing symmetric planar graphs

    E-Print Network [OSTI]

    Meric, Burak Necati

    1998-01-01T23:59:59.000Z

    16 17 19 20 21 22 23 24 25 26 A drawing generated by repeating graphs. Generation of the drawing with the unit cell. Calculation of the converted lines. Rectangular unit cell for hexagonal groups. Construction ofhexagonal cells by using... of pixels requires much computer memories and much powerful processors. Figure 1. A drawing generated by repeating graphs. Drawing uses an object-oriented point of view. In drawing, patterns are created as a collection of objects such as points, lines...

  4. Probabilistic regular graphs

    E-Print Network [OSTI]

    Bertrand, Nathalie; 10.4204/EPTCS.39.6

    2010-01-01T23:59:59.000Z

    Deterministic graph grammars generate regular graphs, that form a structural extension of configuration graphs of pushdown systems. In this paper, we study a probabilistic extension of regular graphs obtained by labelling the terminal arcs of the graph grammars by probabilities. Stochastic properties of these graphs are expressed using PCTL, a probabilistic extension of computation tree logic. We present here an algorithm to perform approximate verification of PCTL formulae. Moreover, we prove that the exact model-checking problem for PCTL on probabilistic regular graphs is undecidable, unless restricting to qualitative properties. Our results generalise those of EKM06, on probabilistic pushdown automata, using similar methods combined with graph grammars techniques.

  5. Convex Graph Invariants

    E-Print Network [OSTI]

    2010-12-02T23:59:59.000Z

    Dec 2, 2010 ... Massachusetts Institute of Technology ... testing between graph families, and the generation of graphs with certain desired structural properties.

  6. A heuristic algorithm for graph isomorphism

    E-Print Network [OSTI]

    Torres Navarro, Luz

    1999-01-01T23:59:59.000Z

    polynomial time algorithm O(n?), ISO-MT, that seems' to solve the graph isomorphism decision problem correctly for all classes of graphs. Our algorithm is extremely useful from the practical point of view since counter examples (pairs of graphs for which our...

  7. Methods of visualizing graphs

    DOE Patents [OSTI]

    Wong, Pak C. (Richland, WA); Mackey, Patrick S. (Kennewick, WA); Perrine, Kenneth A. (Richland, WA); Foote, Harlan P. (Richland, WA); Thomas, James J. (Richland, WA)

    2008-12-23T23:59:59.000Z

    Methods for visualizing a graph by automatically drawing elements of the graph as labels are disclosed. In one embodiment, the method comprises receiving node information and edge information from an input device and/or communication interface, constructing a graph layout based at least in part on that information, wherein the edges are automatically drawn as labels, and displaying the graph on a display device according to the graph layout. In some embodiments, the nodes are automatically drawn as labels instead of, or in addition to, the label-edges.

  8. Hyperbolic Graph Generator

    E-Print Network [OSTI]

    Aldecoa, Rodrigo; Krioukov, Dmitri

    2015-01-01T23:59:59.000Z

    Networks representing many complex systems in nature and society share some common structural properties like heterogeneous degree distributions and strong clustering. Recent research on network geometry has shown that those real networks can be adequately modeled as random geometric graphs in hyperbolic spaces. In this paper, we present a computer program to generate such graphs. Besides real-world-like networks, the program can generate random graphs from other well-known graph ensembles, such as the soft configuration model, random geometric graphs on a circle, or Erd\\H{o}s-R\\'enyi random graphs. The simulations show a good match between the expected values of different network structural properties and the corresponding empirical values measured in generated graphs, confirming the accurate behavior of the program.

  9. Spectral characterizations of sun graphs and broken sun graphs

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Spectral characterizations of sun graphs and broken sun graphs Romain Boulet 10 Dec 2009 Abstract- cyclic graphs. An odd (resp. even) sun is a graph obtained by appending a pendant vertex to each vertex of an odd (resp. even) cycle. A broken sun is a graph obtained by deleting pendant vertices of a sun

  10. A Unified View of Kernel k-means, Spectral Clustering and Graph Inderjit Dhillon, Yuqiang Guan and Brian Kulis

    E-Print Network [OSTI]

    A Unified View of Kernel k-means, Spectral Clustering and Graph Cuts Inderjit Dhillon, Yuqiang Guan proposed to handle data that is not linearly separable. Spectral clustering and kernel k-means are two such methods that are seemingly quite different. In this paper, we show that a general weighted kernel k-means

  11. Extending graph homomorphism and simulation for real life graph matching 

    E-Print Network [OSTI]

    Wu, Yinghui

    2011-06-30T23:59:59.000Z

    Among the vital problems in a variety of emerging applications is the graph matching problem, which is to determine whether two graphs are similar, and if so, find all the valid matches in one graph for the other, based ...

  12. Graph Generator Survey

    SciTech Connect (OSTI)

    Lothian, Josh [ORNL; Powers, Sarah S [ORNL; Sullivan, Blair D [ORNL; Baker, Matthew B [ORNL; Schrock, Jonathan [ORNL; Poole, Stephen W [ORNL

    2013-12-01T23:59:59.000Z

    The benchmarking effort within the Extreme Scale Systems Center at Oak Ridge National Laboratory seeks to provide High Performance Computing benchmarks and test suites of interest to the DoD sponsor. The work described in this report is a part of the effort focusing on graph generation. A previously developed benchmark, SystemBurn, allowed the emulation of dierent application behavior profiles within a single framework. To complement this effort, similar capabilities are desired for graph-centric problems. This report examines existing synthetic graph generator implementations in preparation for further study on the properties of their generated synthetic graphs.

  13. Graph concatenation for quantum codes

    E-Print Network [OSTI]

    Beigi, Salman

    Graphs are closely related to quantum error-correcting codes: every stabilizer code is locally equivalent to a graph code and every codeword stabilized code can be described by a graph and a classical code. For the ...

  14. Vacuum Energy in Quantum Graphs

    E-Print Network [OSTI]

    Wilson, Justin

    2007-07-14T23:59:59.000Z

    We calculate the vacuum energy in quantum graphs. Vacuum energy arose in quantum physics but has an independent mathematical interest as a functional carrying information about the eigenvalue spectrum of a system. A quantum graph is a metric graph...

  15. Graph anomalies in cyber communications

    SciTech Connect (OSTI)

    Vander Wiel, Scott A [Los Alamos National Laboratory; Storlie, Curtis B [Los Alamos National Laboratory; Sandine, Gary [Los Alamos National Laboratory; Hagberg, Aric A [Los Alamos National Laboratory; Fisk, Michael [Los Alamos National Laboratory

    2011-01-11T23:59:59.000Z

    Enterprises monitor cyber traffic for viruses, intruders and stolen information. Detection methods look for known signatures of malicious traffic or search for anomalies with respect to a nominal reference model. Traditional anomaly detection focuses on aggregate traffic at central nodes or on user-level monitoring. More recently, however, traffic is being viewed more holistically as a dynamic communication graph. Attention to the graph nature of the traffic has expanded the types of anomalies that are being sought. We give an overview of several cyber data streams collected at Los Alamos National Laboratory and discuss current work in modeling the graph dynamics of traffic over the network. We consider global properties and local properties within the communication graph. A method for monitoring relative entropy on multiple correlated properties is discussed in detail.

  16. Distribution of Agents with Multiple Capabilities in Heterogeneous Multiagent Networks A Graph Theoretic View

    E-Print Network [OSTI]

    Egerstedt, Magnus

    Distribution of Agents with Multiple Capabilities in Heterogeneous Multiagent Networks ­ A Graph networks. I. INTRODUCTION One of the challenges in heterogeneous networks is to optimally distribute agents more fundamental concern is if such a distribution is possible at all for a given network topology. We

  17. A Graph Bottleneck Inequality

    E-Print Network [OSTI]

    Chebotarev, Pavel

    2008-01-01T23:59:59.000Z

    For a weighted multidigraph, let $f_{ij}$ be the total weight of spanning converging forests that have vertex $i$ in a tree converging to $j$. We prove that $f_{ij}f_{jk}=f_{ik}f_{jj}$ if and only if every directed path from $i$ to $k$ contains $j$ (a graph bottleneck equality). Otherwise, $f_{ij}f_{jk}inequality). In a companion paper, this inequality provides the foundation for the construction of a new family of graph distances by ensuring the fulfillment of the triangle inequality. This stems from the fact that the graph bottleneck inequality is a multiplicative analogue of the triangle inequality for proximities.

  18. Efficiently Controllable Graphs

    E-Print Network [OSTI]

    Can Gokler; Kevin Thompson; Peter Shor; Seth Lloyd

    2015-03-18T23:59:59.000Z

    We show that universal quantum computation can be performed efficiently on quantum networks while the fraction of controlled subsystems vanishes as the network grows larger. We provide examples of quantum spin network families admitting polynomial quantum gate complexity with a vanishing fraction of controlled spins. We define a new family of graphs, the efficiently controllable family, which admits efficient computation with vanishing fraction of controls. We explore generalizations to percolation clusters, fractals and random graphs. We show that the classical computational complexity of estimating the ground state of Hamiltonians described by controllable graphs is polynomial in the number of subsystems/qubits.

  19. Graphs associated with semigroups

    E-Print Network [OSTI]

    Baber, Stephen Asa

    1976-01-01T23:59:59.000Z

    to the graph of this system as well. We first consider the question of when G(g ) is a com- 3 19 piete graph. The more general question of connectedness will be considered later' In order to state the next few results we need a definitions A minimal right... tM2. In [2], Clifford and Preston show that any two idempotent elements in an inverse semigroup commute. Thus, complete graph. ele2=e2el e MI()M2. As above, G(4 ) is a In order to show that the four conditions in corollary 4. 3...

  20. Geometry of graph varieties

    E-Print Network [OSTI]

    Martin, Jeremy L.

    2003-01-01T23:59:59.000Z

    (G)isasetofedges, or unordered pairs of distinct verticesfv;wg.Wefrequently abbreviatefv;wgby vw when no confusion can arise (for instance, when the vertices are one-digit positive integers). The vertices v;w are called the endpoints of the edge vw.Asubgraph of G is a graph G 0... =(V 0 ;E 0 )withV 0 V and E 0 E.We de ne K(V 0 )=fvw j v;w2V 0 ;v6= wg and E(V 0 )=E\\K(V 0 ): The complete graph on V is the graph (V;K(V)). We write K n for the complete graph onf1;:::;ng.ForE 0 E and v2V,thevalence of v with respect to E 0 is val...

  1. Querying graphs with data 

    E-Print Network [OSTI]

    Vrgoc, Domagoj

    2014-06-27T23:59:59.000Z

    Graph data is becoming more and more pervasive. Indeed, services such as Social Networks or the Semantic Web can no longer rely on the traditional relational model, as its structure is somewhat too rigid for the applications ...

  2. Graph similarity and matching

    E-Print Network [OSTI]

    Zager, Laura (Laura A.)

    2005-01-01T23:59:59.000Z

    Measures of graph similarity have a broad array of applications, including comparing chemical structures, navigating complex networks like the World Wide Web, and more recently, analyzing different kinds of biological data. ...

  3. Graphing at Pepco

    SciTech Connect (OSTI)

    Not Available

    1984-11-01T23:59:59.000Z

    Pepco's $250,000 worth of computer-graphics equipment has let the utility produce 60 to 100 graphs a day, for everyone from engineers to executives. The types and uses of computer graphics equipment are discussed.

  4. Graph Concatenation for Quantum Codes

    E-Print Network [OSTI]

    Salman Beigi; Isaac Chuang; Markus Grassl; Peter Shor; Bei Zeng

    2010-02-03T23:59:59.000Z

    Graphs are closely related to quantum error-correcting codes: every stabilizer code is locally equivalent to a graph code, and every codeword stabilized code can be described by a graph and a classical code. For the construction of good quantum codes of relatively large block length, concatenated quantum codes and their generalizations play an important role. We develop a systematic method for constructing concatenated quantum codes based on "graph concatenation", where graphs representing the inner and outer codes are concatenated via a simple graph operation called "generalized local complementation." Our method applies to both binary and non-binary concatenated quantum codes as well as their generalizations.

  5. Graph dynamics : learning and representation

    E-Print Network [OSTI]

    Ribeiro, Andre Figueiredo

    2006-01-01T23:59:59.000Z

    Graphs are often used in artificial intelligence as means for symbolic knowledge representation. A graph is nothing more than a collection of symbols connected to each other in some fashion. For example, in computer vision ...

  6. Temporal Representation in Semantic Graphs

    SciTech Connect (OSTI)

    Levandoski, J J; Abdulla, G M

    2007-08-07T23:59:59.000Z

    A wide range of knowledge discovery and analysis applications, ranging from business to biological, make use of semantic graphs when modeling relationships and concepts. Most of the semantic graphs used in these applications are assumed to be static pieces of information, meaning temporal evolution of concepts and relationships are not taken into account. Guided by the need for more advanced semantic graph queries involving temporal concepts, this paper surveys the existing work involving temporal representations in semantic graphs.

  7. Densities in graphs and matroids

    E-Print Network [OSTI]

    Kannan, Lavanya

    2009-05-15T23:59:59.000Z

    Certain graphs can be described by the distribution of the edges in its subgraphs. For example, a cycle C is a graph that satisfies |E(H)| |V (H)| < |E(C)| |V (C)| = 1 for all non-trivial subgraphs of C. Similarly, a tree T is a graph that satisfies...

  8. Spectral fluctuations of quantum graphs

    SciTech Connect (OSTI)

    Pluha?, Z. [Faculty of Mathematics and Physics, Charles University, 180 00 Praha 8 (Czech Republic); Weidenmüller, H. A. [Max-Planck-Institut für Kernphysik, 69029 Heidelberg (Germany)

    2014-10-15T23:59:59.000Z

    We prove the Bohigas-Giannoni-Schmit conjecture in its most general form for completely connected simple graphs with incommensurate bond lengths. We show that for graphs that are classically mixing (i.e., graphs for which the spectrum of the classical Perron-Frobenius operator possesses a finite gap), the generating functions for all (P,Q) correlation functions for both closed and open graphs coincide (in the limit of infinite graph size) with the corresponding expressions of random-matrix theory, both for orthogonal and for unitary symmetry.

  9. Cliques in graphs

    E-Print Network [OSTI]

    Lo, Allan

    2010-10-12T23:59:59.000Z

    Cliques in Graphs Siu Lun Allan Lo Christ’s College University of Cambridge A thesis submitted for the degree of Doctor of Philosophy 2010 Declaration This dissertation is the result of my own work and includes nothing which is the outcome of work...

  10. Graph Coarsening for Path Finding in Cybersecurity Graphs

    SciTech Connect (OSTI)

    Hogan, Emilie A.; Johnson, John R.; Halappanavar, Mahantesh

    2013-01-01T23:59:59.000Z

    n the pass-the-hash attack, hackers repeatedly steal password hashes and move through a computer network with the goal of reaching a computer with high level administrative privileges. In this paper we apply graph coarsening in network graphs for the purpose of detecting hackers using this attack or assessing the risk level of the network's current state. We repeatedly take graph minors, which preserve the existence of paths in the graph, and take powers of the adjacency matrix to count the paths. This allows us to detect the existence of paths as well as find paths that have high risk of being used by adversaries.

  11. The graph bottleneck identity

    E-Print Network [OSTI]

    Chebotarev, Pavel

    2010-01-01T23:59:59.000Z

    A matrix $S=(s_{ij})_{n\\times n}$ is said to determine a \\emph{transitional measure} for a digraph $\\Gamma$ on $n$ vertices if for all $i,j,k\\in\\{1,...,n\\},$ the \\emph{transition inequality} $s_{ij}s_{jk}\\le s_{ik}s_{jj}$ holds and reduces to the equality (called the \\emph{graph bottleneck identity}) if and only if every path in $\\Gamma$ from $i$ to $k$ contains $j$. We show that every positive transitional measure produces a distance by means of a logarithmic transformation. Moreover, the resulting distance $d(\\cdot,\\cdot)$ is \\emph{graph-geodetic}, that is, $d(i,j)+d(j,k)=d(i,k)$ holds if and only if every path from $i$ to $k$ contains $j$. Five types of matrices that determine transitional measures for a strong digraph are considered, namely, the matrices of path weights, connection reliabilities, route weights, and the weights of in-forests and out-forests. The results obtained have undirected counterparts. In [P. Chebotarev, A family of graph distances generalizing both the shortest-path and the resistan...

  12. Graph/Network Visualization Data model: graph structures (relations,

    E-Print Network [OSTI]

    Fang, Shiaofen

    of physics #12;8 The Spring Model Using springs to represent node-node relations. Minimizing energy1 1 Graph/Network Visualization Data model: graph structures (relations, knowledge) and networks hierarchies #12;7 Sugiyama : Building Hierarchy Domain knowledge based. Designing heuristic, e.g. minimizing

  13. Random rectangular Graphs

    E-Print Network [OSTI]

    Estrada, Ernesto

    2015-01-01T23:59:59.000Z

    A generalization of the random geometric graph (RGG) model is proposed by considering a set of points uniformly and independently distributed on a rectangle of unit area instead of on a unit square \\left[0,1\\right]^{2}. The topological properties, such as connectivity, average degree, average path length and clustering, of the random rectangular graphs (RRGs) generated by this model are then studied as a function of the rectangle sides lengths a and b=1/a, and the radius r used to connect the nodes. When a=1 we recover the RGG, and when a\\rightarrow\\infty the very elongated rectangle generated resembles a one-dimensional RGG. We provided computational and analytical evidence that the topological properties of the RRG differ significantly from those of the RGG. The connectivity of the RRG depends not only on the number of nodes as in the case of the RGG, but also on the side length of the rectangle. As the rectangle is more elongated the critical radius for connectivity increases following first a power-law an...

  14. GRAPH III: a digitizing and graph plotting program

    SciTech Connect (OSTI)

    Selleck, C.B.

    1986-03-01T23:59:59.000Z

    GRAPH is an interactive program that allows the user to perform two functions. The first is to plot two dimensional graphs and the second is to digitize graphs or plots to create data files of points. The program is designed to allow the user to get results quickly and easily. It is written in RATIV (a FORTRAN preprocessor) and is currently in use at Sandia under VMS on a VAX computer and CTSS on a Cray supercomputer. The program provides graphical output through all of the Sandia Virtual Device Interface (VDI) graphics devices. 2 refs., 3 figs., 3 tabs.

  15. Tools for Large Graph Mining Deepayan Chakrabarti

    E-Print Network [OSTI]

    Tools for Large Graph Mining by Deepayan Chakrabarti Submitted to the Center for Automated Learning computer networks to sociology, biology, ecology and many more. How do such "normal" graphs look like? How-graph, which can be both weighted or unweighted. · Ecology: Food webs are self-graphs with each node

  16. Contagious Sets in Random Graphs Uriel Feige

    E-Print Network [OSTI]

    Contagious Sets in Random Graphs Uriel Feige Michael Krivelevich Daniel Reichman August 10, 2014. A contagious set is a set whose activation results with the entire graph being active. Given a graph G, let m(G, 2) be the minimal size of a contagious set. We consider the binomial random graph G := G(n, p

  17. GRAPH THEORY STUDY GUIDE 1. Definitions

    E-Print Network [OSTI]

    Cooper, Joshua N.

    GRAPH THEORY STUDY GUIDE 1. Definitions Definition 1 (Partition of A). A set A = A1, ..., Ak. Definition 2 (Vertex set). The set of vertices in a graph denoted by V (G). Definition 3 (Edge set). The set of edges in a graph denoted by E(G). Definition 4 (Order). the number of vertices of a graph G written |G

  18. A Study on Set-Graphs

    E-Print Network [OSTI]

    Johan Kok; K. P. Chithra; N. K. Sudev; C. Susanth

    2015-04-09T23:59:59.000Z

    A \\textit{primitive hole} of a graph $G$ is a cycle of length $3$ in $G$. The number of primitive holes in a given graph $G$ is called the primitive hole number of that graph $G$. The primitive degree of a vertex $v$ of a given graph $G$ is the number of primitive holes incident on the vertex $v$. In this paper, we introduce the notion of set-graphs and study the properties and characteristics of set-graphs. We also check the primitive hole number and primitive degree of set-graphs. Interesting introductory results on the nature of order of set-graphs, degree of the vertices corresponding to subsets of equal cardinality, the number of largest complete subgraphs in a set-graph etc. are discussed in this study. A recursive formula to determine the primitive hole number of a set-graph is also derived in this paper.

  19. Doing time : inducing temporal graphs

    E-Print Network [OSTI]

    Bramsen, Philip James

    2006-01-01T23:59:59.000Z

    We consider the problem of constructing a directed acyclic graph that encodes temporal relations found in a text. The unit of our analysis is a temporal segment, a fragment of text that maintains temporal coherence. The ...

  20. Virasoro Representations on Fusion Graphs

    E-Print Network [OSTI]

    J. Kellendonk; A. Recknagel

    1992-10-01T23:59:59.000Z

    For any non-unitary model with central charge c(2,q) the path spaces associated to a certain fusion graph are isomorphic to the irreducible Virasoro highest weight modules.

  1. Summing tree graphs at threshold

    SciTech Connect (OSTI)

    Brown, L.S. (Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 (United States))

    1992-11-15T23:59:59.000Z

    The solution of the classical field equation generates the sum of all tree graphs. We show that the classical equation reduces to an easily solved ordinary differential equation for certain multiparticle threshold amplitudes and compute these amplitudes.

  2. Managing Attack Graph Complexity Through Visual Hierarchical Aggregation

    E-Print Network [OSTI]

    Noel, Steven

    Managing Attack Graph Complexity Through Visual Hierarchical Aggregation Steven Noel Center a framework for managing network attack graph complexity through interactive visualization, which includes hierarchical aggregation of graph elements. Aggregation collapses non-overlapping subgraphs of the attack graph

  3. Polynomials associated with graph coloring and orientations

    E-Print Network [OSTI]

    Humpert, Brandon Eugene

    2011-04-26T23:59:59.000Z

    We study colorings and orientations of graphs in two related contexts. Firstly, we generalize Stanley's chromatic symmetric function using the k-balanced colorings of Pretzel to create a new graph invariant. We show that ...

  4. Optimization in Geometric Graphs: Complexity and Approximation

    E-Print Network [OSTI]

    Kahruman-Anderoglu, Sera

    2011-02-22T23:59:59.000Z

    We consider several related problems arising in geometric graphs. In particular, we investigate the computational complexity and approximability properties of several optimization problems in unit ball graphs and develop algorithms to find exact...

  5. Percolation in the Secrecy Graph Amites Sarkar

    E-Print Network [OSTI]

    Sarkar, Amites

    Percolation in the Secrecy Graph Amites Sarkar Martin Haenggi July 8, 2011 Abstract Secrecy graphs. Department of Mathematics, Western Washington University, Bellingham, WA 98225, USA. Email: amites.sarkar

  6. Algebraic connectivity and graph robustness.

    SciTech Connect (OSTI)

    Feddema, John Todd; Byrne, Raymond Harry; Abdallah, Chaouki T. (University of New Mexico)

    2009-07-01T23:59:59.000Z

    Recent papers have used Fiedler's definition of algebraic connectivity to show that network robustness, as measured by node-connectivity and edge-connectivity, can be increased by increasing the algebraic connectivity of the network. By the definition of algebraic connectivity, the second smallest eigenvalue of the graph Laplacian is a lower bound on the node-connectivity. In this paper we show that for circular random lattice graphs and mesh graphs algebraic connectivity is a conservative lower bound, and that increases in algebraic connectivity actually correspond to a decrease in node-connectivity. This means that the networks are actually less robust with respect to node-connectivity as the algebraic connectivity increases. However, an increase in algebraic connectivity seems to correlate well with a decrease in the characteristic path length of these networks - which would result in quicker communication through the network. Applications of these results are then discussed for perimeter security.

  7. Graph Analytics for Signature Discovery

    SciTech Connect (OSTI)

    Hogan, Emilie A.; Johnson, John R.; Halappanavar, Mahantesh; Lo, Chaomei

    2013-06-01T23:59:59.000Z

    Within large amounts of seemingly unstructured data it can be diffcult to find signatures of events. In our work we transform unstructured data into a graph representation. By doing this we expose underlying structure in the data and can take advantage of existing graph analytics capabilities, as well as develop new capabilities. Currently we focus on applications in cybersecurity and communication domains. Within cybersecurity we aim to find signatures for perpetrators using the pass-the-hash attack, and in communications we look for emails or phone calls going up or down a chain of command. In both of these areas, and in many others, the signature we look for is a path with certain temporal properties. In this paper we discuss our methodology for finding these temporal paths within large graphs.

  8. Evan Marshall Trevathan Admissible SC-Graphs

    E-Print Network [OSTI]

    Donnelly, Rob

    Evan Marshall Trevathan Admissible SC-Graphs Page 1 Admissible SC-Graphs Define: ( , )G ( 2)nB n ( 4)nD n ( 6,7,8)nE n 4F 2G 2H 3H #12;Evan Marshall Trevathan Admissible SC-Graphs Page 2 the form of a #12;Evan Marshall Trevathan Admissible SC-Graphs Page 3 "loop", like ,with no other

  9. ALGORITHMS FOR EMBEDDING GRAPHS IN BOOKS

    E-Print Network [OSTI]

    North Carolina at Chapel Hill, University of

    investigate the problem ol embedding graphs in boob. A book is some number or half- planes (the page

  10. On semidefinite programming bounds for graph bandwidth

    E-Print Network [OSTI]

    Etienne De Klerk

    2011-06-06T23:59:59.000Z

    Jun 6, 2011 ... Keywords: Graph bandwidth, cyclic bandwidth, semidefinite programming, quadratic assignment problem. Category 1: Linear, Cone and ...

  11. Minimal Spanning Trees with Conflict Graphs

    E-Print Network [OSTI]

    symmetric conflict relations by means of an undirected conflict graph, where ..... International Symposium on Mathematical Foundations of Computer. Science ...

  12. NLS ground states on graphs

    E-Print Network [OSTI]

    Riccardo Adami; Enrico Serra; Paolo Tilli

    2014-06-16T23:59:59.000Z

    We investigate the existence of ground states for the subcritical NLS energy on metric graphs. In particular, we find out a topological assumption that guarantees the nonexistence of ground states, and give an example in which the assumption is not fulfilled and ground states actually exist. In order to obtain the result, we introduce a new rearrangement technique, adapted to the graph where it applies. Owing to such a technique, the energy level of the rearranged function is improved by conveniently mixing the symmetric and monotone rearrangement procedures.

  13. Effecting Parallel Graph Eigensolvers Through Library Composition

    E-Print Network [OSTI]

    Lumsdaine, Andrew

    is not possible in general. Conventional linear algebra libraries cannot operate on graph data types. Likewise exploitation of this duality. Graph libraries and matrix libraries use different data types, and despiteEffecting Parallel Graph Eigensolvers Through Library Composition Alex Breuer, Peter Gottschling

  14. Graph Decompositions and Secret Sharing Schemes 1

    E-Print Network [OSTI]

    Stinson, Douglas

    Graph Decompositions and Secret Sharing Schemes 1 C. Blundo and A. De Santis Dipartimento di In this paper, we continue a study of secret sharing schemes for access structures based on graphs. Given a graph G, we require that a subset of participants can compute a secret key if they contain an edge of G

  15. Acyclic Coloring of Graphs of Maximum Degree Five: Nine Colors are Enough

    E-Print Network [OSTI]

    Boyer, Edmond

    graphs with "large" girth [BKW99], 1-planar graphs [BKRS01], outerplanar graphs (see for instance [Sop97

  16. EuroComb 2005 DMTCS proc. AE, 2005, 389396 Acyclic Coloring of Graphs of Maximum

    E-Print Network [OSTI]

    Fertin, Guillaume

    for several families F of graphs such as planar graphs [Bor79], planar graphs with "large" girth [BKW99], 1

  17. Acyclic Coloring of Graphs of Maximum Degree Five: Nine Colors are Enough

    E-Print Network [OSTI]

    Fertin, Guillaume

    graphs with ``large'' girth [BKW99], 1­planar graphs [BKRS01], outerplanar graphs (see for instance [Sop

  18. Generalized Graph States Based on Hadamard Matrices

    E-Print Network [OSTI]

    Shawn X Cui; Nengkun Yu; Bei Zeng

    2015-02-25T23:59:59.000Z

    Graph states are widely used in quantum information theory, including entanglement theory, quantum error correction, and one-way quantum computing. Graph states have a nice structure related to a certain graph, which is given by either a stabilizer group or an encoding circuit, both can be directly given by the graph. To generalize graph states, whose stabilizer groups are abelian subgroups of the Pauli group, one approach taken is to study non-abelian stabilizers. In this work, we propose to generalize graph states based on the encoding circuit, which is completely determined by the graph and a Hadamard matrix. We study the entanglement structures of these generalized graph states, and show that they are all maximally mixed locally. We also explore the relationship between the equivalence of Hadamard matrices and local equivalence of the corresponding generalized graph states. This leads to a natural generalization of the Pauli $(X,Z)$ pairs, which characterizes the local symmetries of these generalized graph states. Our approach is also naturally generalized to construct graph quantum codes which are beyond stabilizer codes.

  19. Constrained Graph Optimization: Interdiction and Preservation Problems

    SciTech Connect (OSTI)

    Schild, Aaron V [Los Alamos National Laboratory

    2012-07-30T23:59:59.000Z

    The maximum flow, shortest path, and maximum matching problems are a set of basic graph problems that are critical in theoretical computer science and applications. Constrained graph optimization, a variation of these basic graph problems involving modification of the underlying graph, is equally important but sometimes significantly harder. In particular, one can explore these optimization problems with additional cost constraints. In the preservation case, the optimizer has a budget to preserve vertices or edges of a graph, preventing them from being deleted. The optimizer wants to find the best set of preserved edges/vertices in which the cost constraints are satisfied and the basic graph problems are optimized. For example, in shortest path preservation, the optimizer wants to find a set of edges/vertices within which the shortest path between two predetermined points is smallest. In interdiction problems, one deletes vertices or edges from the graph with a particular cost in order to impede the basic graph problems as much as possible (for example, delete edges/vertices to maximize the shortest path between two predetermined vertices). Applications of preservation problems include optimal road maintenance, power grid maintenance, and job scheduling, while interdiction problems are related to drug trafficking prevention, network stability assessment, and counterterrorism. Computational hardness results are presented, along with heuristic methods for approximating solutions to the matching interdiction problem. Also, efficient algorithms are presented for special cases of graphs, including on planar graphs. The graphs in many of the listed applications are planar, so these algorithms have important practical implications.

  20. Lamplighter groups, de Bruijn graphs, spider-web graphs and their spectra

    E-Print Network [OSTI]

    Rostislav Grigorchuk; Paul-Henry Leemann; Tatiana Nagnibeda

    2015-02-24T23:59:59.000Z

    We describe the infinite family of spider-web graphs $S_{k,M,N }$, $k \\geq 2$, $M \\geq 1$ and $N \\geq 0$, studied in physical literature as tensor products of well-known de Brujin graphs $B_{k,N}$ and cyclic graphs $C_M$ and show that these graphs are Schreier graphs of the lamplighter groups $L_k = Z/kZ \\wr Z$. This allows us to compute their spectra and to identify the infinite limit of $S_{k,M,N}$, as $N, M \\to\\infty$, with the Cayley graph of the lamplighter group $L_k$.

  1. Lamplighter groups, de Bruijn graphs, spider-web graphs and their spectra

    E-Print Network [OSTI]

    Rostislav Grigorchuk; Paul-Henry Leemann; Tatiana Nagnibeda

    2015-05-05T23:59:59.000Z

    We describe the infinite family of spider-web graphs $S_{k,M,N }$, $k \\geq 2$, $M \\geq 1$ and $N \\geq 0$, studied in physical literature as tensor products of well-known de Brujin graphs $B_{k,N}$ and cyclic graphs $C_M$ and show that these graphs are Schreier graphs of the lamplighter groups $L_k = Z/kZ \\wr Z$. This allows us to compute their spectra and to identify the infinite limit of $S_{k,M,N}$, as $N, M \\to\\infty$, with the Cayley graph of the lamplighter group $L_k$.

  2. On graphs whose Laplacian matrix's multipartite separability is invariant under graph isomorphism

    E-Print Network [OSTI]

    Chai Wah Wu

    2009-06-04T23:59:59.000Z

    Normalized Laplacian matrices of graphs have recently been studied in the context of quantum mechanics as density matrices of quantum systems. Of particular interest is the relationship between quantum physical properties of the density matrix and the graph theoretical properties of the underlying graph. One important aspect of density matrices is their entanglement properties, which are responsible for many nonintuitive physical phenomena. The entanglement property of normalized Laplacian matrices is in general not invariant under graph isomorphism. In recent papers, graphs were identified whose entanglement and separability properties are invariant under isomorphism. The purpose of this note is to characterize the set of graphs whose separability is invariant under graph isomorphism. In particular, we show that this set consists of $K_{2,2}$, $\\overline{K_{2,2}}$ and all complete graphs.

  3. A Feasible Graph Partition Framework for Random Walks Implemented by Parallel Computing in Big Graph

    E-Print Network [OSTI]

    Liu, Xiaoming; Guan, Xiaohong

    2015-01-01T23:59:59.000Z

    Graph partition is a fundamental problem of parallel computing for big graph data. Many graph partition algorithms have been proposed to solve the problem in various applications, such as matrix computations and PageRank, etc., but none has pay attention to random walks. Random walks is a widely used method to explore graph structure in lots of fields. The challenges of graph partition for random walks include the large number of times of communication between partitions, lots of replications of the vertices, unbalanced partition, etc. In this paper, we propose a feasible graph partition framework for random walks implemented by parallel computing in big graph. The framework is based on two optimization functions to reduce the bandwidth, memory and storage cost in the condition that the load balance is guaranteed. In this framework, several greedy graph partition algorithms are proposed. We also propose five metrics from different perspectives to evaluate the performance of these algorithms. By running the al...

  4. Multipartite separability of Laplacian matrices of graphs

    E-Print Network [OSTI]

    Chai Wah Wu

    2008-09-04T23:59:59.000Z

    Recently, Braunstein et al. [1] introduced normalized Laplacian matrices of graphs as density matrices in quantum mechanics and studied the relationships between quantum physical properties and graph theoretical properties of the underlying graphs. We provide further results on the multipartite separability of Laplacian matrices of graphs. In particular, we identify complete bipartite graphs whose normalized Laplacian matrix is multipartite entangled under any vertex labeling. Furthermore, we give conditions on the vertex degrees such that there is a vertex labeling under which the normalized Laplacian matrix is entangled. These results address an open question raised in [1]. Finally, we extend some of the results in [1,2] to the multipartite case and show that the Laplacian matrix of any product of graphs (strong, Cartesian, tensor, categorical, etc.) is multipartite separable.

  5. Median graph shift: A new clustering algorithm for graph domain Salim Jouili, Salvatore Tabbone

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    and a comparison with the well-known Kmeans algorithm is provided. I. INTRODUCTION Graphs give a universal

  6. Discussiones Mathematicae Graph Theory 34 (2014) 287307

    E-Print Network [OSTI]

    Al Hanbali, Ahmad

    2014-01-01T23:59:59.000Z

    FOR TRACEABILITY OF BLOCK-CHAINS Binlong Lia,b1, Hajo Broersmab and Shenggui Zhanga2 a Department of Applied at least n-1 in G. A block-chain is a graph whose block graph is a path, i.e., it is either a P1, P2, every traceable graph is a block-chain, but the reverse does not hold. In this paper we characterize all

  7. 3D Graph Visualization with the Oculus Rift Virtual Graph Reality

    E-Print Network [OSTI]

    Wismath, Stephen

    reality environment such as a CAVE, or · printed as a physical model with a 3D printer. Early studies3D Graph Visualization with the Oculus Rift Virtual Graph Reality Farshad Barahimi, Stephen Wismath regarding three- dimensional (3D) representations of graphs. However, the actual usefulness of such 3D

  8. Spectral statistics of nearly unidirectional quantum graphs

    E-Print Network [OSTI]

    Maram Akila; Boris Gutkin

    2015-03-04T23:59:59.000Z

    The energy levels of a quantum graph with time reversal symmetry and unidirectional classical dynamics are doubly degenerate and obey the spectral statistics of the Gaussian Unitary Ensemble. These degeneracies, however, are lifted when the unidirectionality is broken in one of the graph's vertices by a singular perturbation. Based on a Random Matrix model we derive an analytic expression for the nearest neighbour distribution between energy levels of such systems. As we demonstrate the result agrees excellently with the actual statistics for graphs with a uniform distribution of eigenfunctions. Yet, it exhibits quite substantial deviations for classes of graphs which show strong scarring.

  9. Generation of graph-state streams

    E-Print Network [OSTI]

    Daniel Ballester; Jaeyoon Cho; M. S. Kim

    2010-12-08T23:59:59.000Z

    We propose a protocol to generate a stream of mobile qubits in a graph state through a single stationary parent qubit and discuss two types of its physical implementation, namely, the generation of photonic graph states through an atom-like qubit and those of flying atoms through a cavity-mode photonic qubit. The generated graph states fall into an important class that can hugely reduce the resource requirement of fault-tolerant linear optics quantum computation, which was previously known to be far from realistic. In regard to the flying atoms, we also propose a heralded generation scheme, which allows for high-fidelity graph states even under the photon loss.

  10. Graph algorithms in the titan toolkit.

    SciTech Connect (OSTI)

    McLendon, William Clarence, III; Wylie, Brian Neil

    2009-10-01T23:59:59.000Z

    Graph algorithms are a key component in a wide variety of intelligence analysis activities. The Graph-Based Informatics for Non-Proliferation and Counter-Terrorism project addresses the critical need of making these graph algorithms accessible to Sandia analysts in a manner that is both intuitive and effective. Specifically we describe the design and implementation of an open source toolkit for doing graph analysis, informatics, and visualization that provides Sandia with novel analysis capability for non-proliferation and counter-terrorism.

  11. Nuclear reactor multiphysics via bond graph formalism

    E-Print Network [OSTI]

    Sosnovsky, Eugeny

    2014-01-01T23:59:59.000Z

    This work proposes a simple and effective approach to modeling nuclear reactor multiphysics problems using bond graphs. Conventional multiphysics simulation paradigms normally use operator splitting, which treats the ...

  12. On the Cohen-Macaulay graphs and girth

    E-Print Network [OSTI]

    Hoang, Do Trong; Trung, Tran Nam

    2012-01-01T23:59:59.000Z

    In this paper we investigate the Cohen-Macaulay property of graphs versus girth. In particular, we classify Cohen-Macaulay graphs of girth at least five and planar Gorenstein graphs of girth four.

  13. Operational Equivalence of Graph Transformation Systems

    E-Print Network [OSTI]

    Sarna-Starosta, Beata

    Operational Equivalence of Graph Transformation Systems Frank Raiser and Thom Fr¨uhwirth Faculty. With the growing number of GTS- based applications the comparison of operational equivalence of two GTS becomes an important area of research. This work introduces a notion of operational equivalence for graph

  14. On terminal deltawye reducibility of planar graphs

    E-Print Network [OSTI]

    Sagols, Feliú

    On terminal delta­wye reducibility of planar graphs Isidoro Gitler1 Feli´u Sagols2 Departamento de´exico City, D.F. igitler@math.cinvestav.mx fsagols@math.cinvestav.mx Abstract A graph is terminal - Y -reducible if it can be reduced to a set of terminal vertices by a sequence of series-parallel reductions

  15. A COLUMN GENERATION APPROACH FOR GRAPH COLORING

    E-Print Network [OSTI]

    Grossmann, Ignacio E.

    set in the graph). We use a column generation method for implicit optimization of the linear program based on an integer programming formulation of the graph coloring problem. This formulation, called is an assignment of labels to each vertex such that the endpoints of any edge have different labels. A minimum

  16. A Count of Classical Field Theory Graphs

    E-Print Network [OSTI]

    Gordon Chalmers

    2005-07-28T23:59:59.000Z

    A generating function is derived that counts the number of diagrams in an arbitrary scalar field theory. The number of graphs containing any number $n_j$ of $j$-point vertices is given. The count is also used to obtain the number of classical graphs in gauge theory and gravity.

  17. Directed Graphs, Decompositions, and Spatial Linkages

    E-Print Network [OSTI]

    Shai, Offer; Whiteley, Walter

    2010-01-01T23:59:59.000Z

    The decomposition of a system of constraints into small basic components is an important tool of design and analysis. Specifically, the decomposition of a linkage into minimal components is a central tool of analysis and synthesis of linkages. In this paper we prove that every pinned 3-isostatic (minimally rigid) graph (grounded linkage) has a unique decomposition into minimal strongly connected components (in the sense of directed graphs) which we call 3-Assur graphs. This analysis extends the Assur decompositions of plane linkages previously studied in the mathematical and the mechanical engineering literature. These 3-Assur graphs are the central building blocks for all kinematic linkages in 3-space. They share a number of key combinatorial and geometric properties with the 2-Assur graphs, including an associated lower block-triangular decomposition of the pinned rigidity matrix which provides a format for extending the motion induced by inserting one driver in a bottom Assur linkage to the joints of the e...

  18. Clustering attributed graphs: models, measures and methods

    E-Print Network [OSTI]

    Bothorel, Cecile; Magnani, Matteo; Micenkova, Barbora

    2015-01-01T23:59:59.000Z

    Clustering a graph, i.e., assigning its nodes to groups, is an important operation whose best known application is the discovery of communities in social networks. Graph clustering and community detection have traditionally focused on graphs without attributes, with the notable exception of edge weights. However, these models only provide a partial representation of real social systems, that are thus often described using node attributes, representing features of the actors, and edge attributes, representing different kinds of relationships among them. We refer to these models as attributed graphs. Consequently, existing graph clustering methods have been recently extended to deal with node and edge attributes. This article is a literature survey on this topic, organizing and presenting recent research results in a uniform way, characterizing the main existing clustering methods and highlighting their conceptual differences. We also cover the important topic of clustering evaluation and identify current open ...

  19. EuroComb 2005 DMTCS proc. AE, 2005, 389--396 Acyclic Coloring of Graphs of Maximum

    E-Print Network [OSTI]

    Fertin, Guillaume

    for several families F of graphs such as planar graphs [Bor79], planar graphs with ``large'' girth [BKW99], 1

  20. Vienna Graph Template Library Version 1.0

    E-Print Network [OSTI]

    Neumaier, Arnold

    .1 Vienna Graph Template Library Modules Here is a list of all modules: Classes and types for external useVienna Graph Template Library Version 1.0 Reference Manual Hermann Schichl University of Vienna.2.14 #12;CONTENTS 1 Contents 1 Introduction 1 2 Vienna Graph Template Library Module Index 2 3 Vienna Graph

  1. Attack Graphs for Sensor Placement, Alert Prioritization, and Attack Response

    E-Print Network [OSTI]

    Noel, Steven

    1 Attack Graphs for Sensor Placement, Alert Prioritization, and Attack Response Steven Noel of IDS alarms, using attack graph analysis. Our attack graphs predict the various possible ways and attacker exploits provides an attack graph showing all possible paths to critical assets. We then place IDS

  2. Graph partitioning advance clustering technique

    E-Print Network [OSTI]

    Madhulatha, T Soni

    2012-01-01T23:59:59.000Z

    Clustering is a common technique for statistical data analysis, Clustering is the process of grouping the data into classes or clusters so that objects within a cluster have high similarity in comparison to one another, but are very dissimilar to objects in other clusters. Dissimilarities are assessed based on the attribute values describing the objects. Often, distance measures are used. Clustering is an unsupervised learning technique, where interesting patterns and structures can be found directly from very large data sets with little or none of the background knowledge. This paper also considers the partitioning of m-dimensional lattice graphs using Fiedler's approach, which requires the determination of the eigenvector belonging to the second smallest Eigenvalue of the Laplacian with K-means partitioning algorithm.

  3. A role for matrices in graph theory

    E-Print Network [OSTI]

    McLean, John Patrick

    1971-01-01T23:59:59.000Z

    Theory are well established areas in mathematics, much remains to be done in the standardization of notation and conventions. Thus we begin by defining terms to be used in this Thesis. 1. ) ~Gh 1'h By the directed graph G(X, r), or simply G, we mean... directed graph is said to be stronglb connected if for each pair of vertices x and x. , there is a path from xi to x ~ If Z is a subset of X and TZ is the subfunction of I' from Z into Z, then G'(Z, "Z) is a subgz'aph of G. The bi-partite graph G(X, Y...

  4. Revisiting Interval Graphs for Network Science

    E-Print Network [OSTI]

    Loe, Chuan Wen

    2015-01-01T23:59:59.000Z

    The vertices of an interval graph represent intervals over a real line where overlapping intervals denote that their corresponding vertices are adjacent. This implies that the vertices are measurable by a metric and there exists a linear structure in the system. The generalization is an embedding of a graph onto a multi-dimensional Euclidean space and it was used by scientists to study the multi-relational complexity of ecology. However the research went out of fashion in the 1980s and was not revisited when Network Science recently expressed interests with multi-relational networks known as multiplexes. This paper studies interval graphs from the perspective of Network Science.

  5. From graphs to signals and back: Identification of graph structures using spectral analysis

    E-Print Network [OSTI]

    Hamon, Ronan; Flandrin, Patrick; Robardet, Céline

    2015-01-01T23:59:59.000Z

    Many systems comprising entities in interactions can be represented as graphs, whose structure gives significant insights about how these systems work. Network theory has undergone further developments, in particular in relation to detection of communities in graphs, to catch this structure. Recently, an approach has been proposed to transform a graph into a collection of signals: Using a multidimensional scaling technique on a distance matrix representing relations between vertices of the graph, points in a Euclidean space are obtained and interpreted as signals, indexed by the vertices. In this article, we propose several extensions to this approach, developing a framework to study graph structures using signal processing tools. We first extend the current methodology, enabling us to highlight connections between properties of signals and graph structures, such as communities, regularity or randomness, as well as combinations of those. A robust inverse transformation method is next described, taking into ac...

  6. Werner Trobin, May 26, 2004 The Boost Graph Library -p. 1/48 The Boost Graph Library

    E-Print Network [OSTI]

    Werner Trobin, May 26, 2004 The Boost Graph Library - p. 1/48 The Boost Graph Library Generic Library Design Werner Trobin #12;Introduction The Boost Graph Library Demo References Werner Trobin, May 26, 2004 The Boost Graph Library - p. 2/48 Outline I Introduction to Boost I The Boost

  7. Continuous-time quantum walks on star graphs

    SciTech Connect (OSTI)

    Salimi, S. [Department of Physics, University of Kurdistan, P.O. Box 66177-15175, Sanandaj (Iran, Islamic Republic of)], E-mail: shsalimi@uok.ac.ir

    2009-06-15T23:59:59.000Z

    In this paper, we investigate continuous-time quantum walk on star graphs. It is shown that quantum central limit theorem for a continuous-time quantum walk on star graphs for N-fold star power graph, which are invariant under the quantum component of adjacency matrix, converges to continuous-time quantum walk on K{sub 2} graphs (complete graph with two vertices) and the probability of observing walk tends to the uniform distribution.

  8. On semidefinite programming bounds for graph bandwidth

    E-Print Network [OSTI]

    2011-05-24T23:59:59.000Z

    May 24, 2011 ... the rectangular grid graph Pn × Pm (i.e. the Cartesian product of the paths Pn and Pm) is min{n, m} [6] ...... Ars Combinatoria, 47:147-152, 1997.

  9. Constant time algorithms in sparse graph model

    E-Print Network [OSTI]

    Nguyen, Huy Ngoc, Ph. D. Massachusetts Institute of Technology

    2010-01-01T23:59:59.000Z

    We focus on constant-time algorithms for graph problems in bounded degree model. We introduce several techniques to design constant-time approximation algorithms for problems such as Vertex Cover, Maximum Matching, Maximum ...

  10. Forced orientation of graphs Babak Farzad

    E-Print Network [OSTI]

    Toronto, University of

    Forced orientation of graphs Babak Farzad Mohammad Mahdian Ebad S. Mahmoodian Amin Saberi§ Bardia, USA. (saberi@cc.gatech.edu) ¶ Department of Computer Science, UIUC, Urbana, USA. (sadri@cs.uiuc.edu) 1

  11. Support graph preconditioners for sparse linear systems

    E-Print Network [OSTI]

    Gupta, Radhika

    2005-02-17T23:59:59.000Z

    . In this thesis, we develop support graph preconditioners for symmetric positive de?nite matrices that arise from the ?nite element discretization of elliptic partial di?erential equations. An object oriented code is developed for the construction, integration...

  12. Fault-tolerant dynamic task graph scheduling

    SciTech Connect (OSTI)

    Kurt, Mehmet C.; Krishnamoorthy, Sriram; Agrawal, Kunal; Agrawal, Gagan

    2014-11-16T23:59:59.000Z

    In this paper, we present an approach to fault tolerant execution of dynamic task graphs scheduled using work stealing. In particular, we focus on selective and localized recovery of tasks in the presence of soft faults. We elicit from the user the basic task graph structure in terms of successor and predecessor relationships. The work stealing-based algorithm to schedule such a task graph is augmented to enable recovery when the data and meta-data associated with a task get corrupted. We use this redundancy, and the knowledge of the task graph structure, to selectively recover from faults with low space and time overheads. We show that the fault tolerant design retains the essential properties of the underlying work stealing-based task scheduling algorithm, and that the fault tolerant execution is asymptotically optimal when task re-execution is taken into account. Experimental evaluation demonstrates the low cost of recovery under various fault scenarios.

  13. Projective representations from quantum enhanced graph symmetries

    E-Print Network [OSTI]

    2015-03-11T23:59:59.000Z

    Presently, we will label the edges of a graph by elements of a group ...... (a) Read off the matrix ? by putting the G label of a vertex onto the diagonal in the place.

  14. Continuous Time Group Discovery in Dynamic Graphs

    SciTech Connect (OSTI)

    Miller, K; Eliassi-Rad, T

    2010-11-04T23:59:59.000Z

    With the rise in availability and importance of graphs and networks, it has become increasingly important to have good models to describe their behavior. While much work has focused on modeling static graphs, we focus on group discovery in dynamic graphs. We adapt a dynamic extension of Latent Dirichlet Allocation to this task and demonstrate good performance on two datasets. Modeling relational data has become increasingly important in recent years. Much work has focused on static graphs - that is fixed graphs at a single point in time. Here we focus on the problem of modeling dynamic (i.e. time-evolving) graphs. We propose a scalable Bayesian approach for community discovery in dynamic graphs. Our approach is based on extensions of Latent Dirichlet Allocation (LDA). LDA is a latent variable model for topic modeling in text corpora. It was extended to deal with topic changes in discrete time and later in continuous time. These models were referred to as the discrete Dynamic Topic Model (dDTM) and the continuous Dynamic Topic Model (cDTM), respectively. When adapting these models to graphs, we take our inspiration from LDA-G and SSN-LDA, applications of LDA to static graphs that have been shown to effectively factor out community structure to explain link patterns in graphs. In this paper, we demonstrate how to adapt and apply the cDTM to the task of finding communities in dynamic networks. We use link prediction to measure the quality of the discovered community structure and apply it to two different relational datasets - DBLP author-keyword and CAIDA autonomous systems relationships. We also discuss a parallel implementation of this approach using Hadoop. In Section 2, we review LDA and LDA-G. In Section 3, we review the cDTM and introduce cDTMG, its adaptation to modeling dynamic graphs. We discuss inference for the cDTM-G and details of our parallel implementation in Section 4 and present its performance on two datasets in Section 5 before concluding in Section 6.

  15. 2Cosmic Bar Graphs Galaxy Type

    E-Print Network [OSTI]

    in the cluster are spirals? Problem 2 ­ Gamma-ray bursts happen about once each day. The bar graph to the right there are 160 total galaxies, the fraction of spirals is 137/160 = 0.86, or equivalently 86%. Problem 2 ­ Gamma-ray2Cosmic Bar Graphs 0 20 40 60 80 100 S E SB I Galaxy Type Number 0 200 400 600 800 1000 FB SB Burst

  16. Accelerating semantic graph databases on commodity clusters

    SciTech Connect (OSTI)

    Morari, Alessandro; Castellana, Vito G.; Haglin, David J.; Feo, John T.; Weaver, Jesse R.; Tumeo, Antonino; Villa, Oreste

    2013-10-06T23:59:59.000Z

    We are developing a full software system for accelerating semantic graph databases on commodity cluster that scales to hundreds of nodes while maintaining constant query throughput. Our framework comprises a SPARQL to C++ compiler, a library of parallel graph methods and a custom multithreaded runtime layer, which provides a Partitioned Global Address Space (PGAS) programming model with fork/join parallelism and automatic load balancing over a commodity clusters. We present preliminary results for the compiler and for the runtime.

  17. Graphs of subgroups of free groups

    E-Print Network [OSTI]

    Louder, Larsen

    2009-01-01T23:59:59.000Z

    We construct an efficient model for graphs of finitely generated subgroups of free groups. Using this we give a very short proof of Dicks's reformulation of the strengthened Hanna Neumann Conjecture as the Amalgamated Graph Conjecture. In addition, we answer a question of Culler and Shalen on ranks of intersections in free groups. The latter has also been done independently by R. P. Kent IV.

  18. Graph representation of protein free energy landscape

    SciTech Connect (OSTI)

    Li, Minghai; Duan, Mojie; Fan, Jue; Huo, Shuanghong, E-mail: shuo@clarku.edu [Gustaf H. Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, Massachusetts 01610 (United States)] [Gustaf H. Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, Massachusetts 01610 (United States); Han, Li [Department of Mathematics and Computer Science, Clark University, 950 Main Street, Worcester, Massachusetts 01610 (United States)] [Department of Mathematics and Computer Science, Clark University, 950 Main Street, Worcester, Massachusetts 01610 (United States)

    2013-11-14T23:59:59.000Z

    The thermodynamics and kinetics of protein folding and protein conformational changes are governed by the underlying free energy landscape. However, the multidimensional nature of the free energy landscape makes it difficult to describe. We propose to use a weighted-graph approach to depict the free energy landscape with the nodes on the graph representing the conformational states and the edge weights reflecting the free energy barriers between the states. Our graph is constructed from a molecular dynamics trajectory and does not involve projecting the multi-dimensional free energy landscape onto a low-dimensional space defined by a few order parameters. The calculation of free energy barriers was based on transition-path theory using the MSMBuilder2 package. We compare our graph with the widely used transition disconnectivity graph (TRDG) which is constructed from the same trajectory and show that our approach gives more accurate description of the free energy landscape than the TRDG approach even though the latter can be organized into a simple tree representation. The weighted-graph is a general approach and can be used on any complex system.

  19. Intro Algo ring Arbitrary graphs Conclusion PING PONG IN DANGEROUS GRAPHS

    E-Print Network [OSTI]

    Fondements et Applications, Université Paris 7

    Intro Algo ring Arbitrary graphs Conclusion PING PONG IN DANGEROUS GRAPHS Optimal Black Hole Search blocking and destroying any mobile agent entering it. Motivations : Site which is destroyed or dangerous blocking and destroying any mobile agent entering it. Motivations : Site which is destroyed or dangerous

  20. A New Combinatorial Approach for Sparse Graph Problems

    E-Print Network [OSTI]

    Blelloch, Guy E.

    A New Combinatorial Approach for Sparse Graph Problems Guy E. Blelloch, Virginia Vassilevska- totic improvement over O(mn) for all pairs least common ancestors on directed acyclic graphs. 1

  1. Outline of the talk Statistics on Graphs, Exponential Formula and

    E-Print Network [OSTI]

    Poinsot, Laurent

    Outline of the talk Statistics on Graphs, Exponential Formula and Combinatorial Physics G and Complexity" Laurent Poinsot Statistics on Graphs, Exponential Formula and Combinatorial Physics #12;Exponential Formula : Informal Version Ingredients for the exponential formula Partial commutative monoids

  2. On perfect codes in Cartesian product of graphs Michel Mollard

    E-Print Network [OSTI]

    Boyer, Edmond

    ] and others. The existence of perfect codes have also been proved in Towers of Hanoi graphs [6] and Sierpinski on the symmetric group Sn+1 thus are of order (n + 1)!. These families include star graphs, for which the existence

  3. Codes on Graphs: Duality and MacWilliams Identities

    E-Print Network [OSTI]

    Forney, G. David, Jr.

    A conceptual framework involving partition functions of normal factor graphs is introduced, paralleling a similar recent development by Al-Bashabsheh and Mao. The partition functions of dual normal factor graphs are shown ...

  4. Generating Random Graphs with Large Girth Mohsen Bayati

    E-Print Network [OSTI]

    Saberi, Amin

    Generating Random Graphs with Large Girth Mohsen Bayati Andrea Montanari Amin Saberi Abstract We; saberi@stanford.edu. 1 #12;free graphs are close to bipartite. We show that our new algorithm guarantees

  5. GARNET : a Graphical Attack graph and Reachability Network Evaluation Tool

    E-Print Network [OSTI]

    Williams, Leevar (Leevar Christoff)

    2008-01-01T23:59:59.000Z

    Attack graphs are valuable tools in the assessment of network security, revealing potential attack paths an adversary could use to gain control of network assets. Creating an effective visualization for attack graphs is ...

  6. Scalable Parallel Algorithms for Massive Scale-free Graphs

    E-Print Network [OSTI]

    Pearce, Roger Allan

    2013-12-05T23:59:59.000Z

    , distributed, and external memory. This dissertation develops new techniques to parallelize the storage, computation, and communication for scale-free graphs with high-degree vertices. Our work facilitates the processing of large real-world graph datasets...

  7. Scalable Parallel Algorithms for Massive Scale-free Graphs 

    E-Print Network [OSTI]

    Pearce, Roger Allan

    2013-12-05T23:59:59.000Z

    , distributed, and external memory. This dissertation develops new techniques to parallelize the storage, computation, and communication for scale-free graphs with high-degree vertices. Our work facilitates the processing of large real-world graph datasets...

  8. Math 564 Graph Theory Fall 2008 Instructor Amites Sarkar

    E-Print Network [OSTI]

    Sarkar, Amites

    Math 564 Graph Theory Fall 2008 Instructor Amites Sarkar Text Pearls in Graph Theory (Dover Edition and Fridays, in 216 Bond Hall. My phone number is 650 7569 and my e-mail is amites.sarkar@wwu.edu #12;

  9. Math 564 Graph Theory Fall 2013 Instructor Amites Sarkar

    E-Print Network [OSTI]

    Sarkar, Amites

    Math 564 Graph Theory Fall 2013 Instructor Amites Sarkar Text Modern Graph Theory B´ela Bollob, Tuesdays, Wednesdays and Fridays, in 216 Bond Hall. My phone number is 650 7569 and my e-mail is amites.sarkar

  10. MadGraph 5 : Going Beyond

    E-Print Network [OSTI]

    Johan Alwall; Michel Herquet; Fabio Maltoni; Olivier Mattelaer; Tim Stelzer

    2011-06-02T23:59:59.000Z

    MadGraph 5 is the new version of the MadGraph matrix element generator, written in the Python programming language. It implements a number of new, efficient algorithms that provide improved performance and functionality in all aspects of the program. It features a new user interface, several new output formats including C++ process libraries for Pythia 8, and full compatibility with FeynRules for new physics models implementation, allowing for event generation for any model that can be written in the form of a Lagrangian. MadGraph 5 builds on the same philosophy as the previous versions, and its design allows it to be used as a collaborative platform where theoretical, phenomenological and simulation projects can be developed and then distributed to the high-energy community. We describe the ideas and the most important developments of the code and illustrate its capabilities through a few simple phenomenological examples.

  11. Problems of Distance-Regular Graphs Hiroshi Suzuki

    E-Print Network [OSTI]

    Xi, Changchang

    . Biggs, Algebraic Graph Theory Second Edition, Cambridge U. P., Cambridge 1993. [16] N. L. Biggs, A. G

  12. The power graph of a group Peter J. Cameron

    E-Print Network [OSTI]

    Burton, Geoffrey R.

    ; graphs are much looser. For example, there are only five different groups with eight elementsThe power graph of a group Peter J. Cameron Queen Mary, University of London LTCC Open Day, 8 January 2010 Groups and graphs A group is an algebraic structure: a set with a bi- nary operation

  13. VGTL (Vienna Graph Template Library) Version 1.1

    E-Print Network [OSTI]

    Schichl, Hermann

    .1 Vienna Graph Template Library Modules Here is a list of all modules: Classes and types for external useVGTL (Vienna Graph Template Library) Version 1.1 Reference Manual Hermann Schichl University June 2003 #12;CONTENTS 1 Contents 1 Introduction 1 2 Vienna Graph Template Library Module Index 2 3

  14. Mining Closed Relational Graphs with Connectivity Constraints X. Jasmine Zhou

    E-Print Network [OSTI]

    Zhou, Xianghong Jasmine

    Mining Closed Relational Graphs with Connectivity Constraints Xifeng Yan X. Jasmine Zhou Jiawei Han relational graphs, how to mine frequent highly connected subgraphs from it? ... G1 G2 Gn pattern Figure 1. Mining Massive Relational Graphs This new problem setting has three major characteristics different from

  15. Inference of Edge Replacement Graph Grammars Jacek P. Kukluk1

    E-Print Network [OSTI]

    Holder, Lawrence B.

    Inference of Edge Replacement Graph Grammars Jacek P. Kukluk1 , Lawrence B. Holder2 , and Diane J@eecs.wsu.edu Abstract We describe an algorithm and experiments for inference of edge replacement graph grammars for inference of Node Replacement Recursive Graph Grammars [7]. In this paper we describe an approach

  16. Optimal IDS Sensor Placement And Alert Prioritization Using Attack Graphs

    E-Print Network [OSTI]

    Noel, Steven

    1 Optimal IDS Sensor Placement And Alert Prioritization Using Attack Graphs Steven Noel and Sushil optimally place intrusion detection system (IDS) sensors and prioritize IDS alerts using attack graph. The set of all such paths through the network constitutes an attack graph, which we aggregate according

  17. Improving Attack Graph Visualization through Data Reduction and Attack Grouping

    E-Print Network [OSTI]

    Ou, Xinming "Simon"

    Improving Attack Graph Visualization through Data Reduction and Attack Grouping John Homer1 Laboratory, USA Abstract. Various tools exist to analyze enterprise network systems and to produce attack graphs detailing how attackers might penetrate into the system. These attack graphs, however, are often

  18. Cellular Algebras and Graph Invariants Based on Quantum Walks

    E-Print Network [OSTI]

    Jamie Smith

    2011-03-01T23:59:59.000Z

    We consider two graph invariants inspired by quantum walks- one in continuous time and one in discrete time. We will associate a matrix algebra called a cellular algebra with every graph. We show that, if the cellular algebras of two graphs have a similar structure, then they are not distinguished by either of the proposed invariants.

  19. Periodic schedules for Unitary Timed Weighted Event Graphs

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Event Graph model (TEG also called marked graphs [5]) and dataflow graphs, oftenly used in the computer questions are polynomially solved for ordinary TEG [1], [5], [6], [8]. In particular, it has been shown that if a TEG is live, there always exists a periodic schedule with the optimal throughput (i.e. with the same

  20. Problems of Distance-Regular Graphs Hiroshi Suzuki

    E-Print Network [OSTI]

    Xi, Changchang

    ­328. [14] H. Suzuki, The Terwilliger algebra associated with a set of vertices in a distance-regular graph, J. Alg. Combin. 22 (2005), 5-38. [15] P. Terwilliger, Distance-regular graphs and (s, c, a, k)-graphs, J. Combin. Th. (B) 34 (1983), 151­164. [16] P. Terwilliger, A new inequality for distance

  1. StreamWorks - A system for Dynamic Graph Search

    SciTech Connect (OSTI)

    Choudhury, Sutanay; Holder, Larry; Chin, George; Ray, Abhik; Beus, Sherman J.; Feo, John T.

    2013-06-11T23:59:59.000Z

    Acting on time-critical events by processing ever growing social media, news or cyber data streams is a major technical challenge. Many of these data sources can be modeled as multi-relational graphs. Mining and searching for subgraph patterns in a continuous setting requires an efficient approach to incremental graph search. The goal of our work is to enable real-time search capabilities for graph databases. This demonstration will present a dynamic graph query system that leverages the structural and semantic characteristics of the underlying multi-relational graph.

  2. Generalized Domination in Graphs with Applications in Wireless Networks

    E-Print Network [OSTI]

    Sung, Je Sang

    2013-12-10T23:59:59.000Z

    ]. Throughout this dissertation, we consider a finite, simple, undirected graph which is denoted by G = (V,E) where V = {1, 2, . . . , n} and (i, j) ? E when vertices i and j are joined by an edge with |E| = m. Order and size of a graph is the number of vertices... vertices. This definition also applies to a complete graph. Menger’s theorem [79] is a basic result of connectivity in finite undirected graph. The vertex-connectivity version of Menger’s theorem for a finite undirected graph G = (V,E) is the following...

  3. Spectral statistics for scaling quantum graphs

    E-Print Network [OSTI]

    Yu. Dabaghian

    2006-08-09T23:59:59.000Z

    The explicit solution to the spectral problem of quantum graphs is used to obtain the exact distributions of several spectral statistics, such as the oscillations of the quantum momentum eigenvalues around the average, $\\delta k_{n}=k_{n}-\\bar k_{n}$, and the nearest neighbor separations, $s_{n}=k_{n}-k_{n-1}$.

  4. Graph-Theoretic Connectivity Control of Mobile

    E-Print Network [OSTI]

    Pappas, George J.

    ]­[23]. This research has given rise to connectivity or topology control algorithms that regulate the transmission powerINVITED P A P E R Graph-Theoretic Connectivity Control of Mobile Robot Networks This paper develops an analysis for groups of vehicles connected by a communication network; control laws are formulated

  5. Dominating Set on Bipartite Graphs Mathieu Liedloff

    E-Print Network [OSTI]

    Liedloff, Mathieu

    .5263n ) time algorithm using polynomial space and an O(1.5137n ) time algorithm using exponential space ) time and polynomial space algorithm, and an O(1.5063n ) time algorithm that uses exponential space. We]). Known results. Given a graph G = (V, E), a subset D V is a dominating set of G if every vertex of V

  6. Quantum secret sharing with qudit graph states

    SciTech Connect (OSTI)

    Keet, Adrian; Fortescue, Ben; Sanders, Barry C. [Institute for Quantum Information Science, University of Calgary, Alberta, T2N 1N4 (Canada); Markham, Damian [LTCI-CNRS, Telecom ParisTech, 37/39 rue Dareau, F-75014 Paris (France)

    2010-12-15T23:59:59.000Z

    We present a unified formalism for threshold quantum secret sharing using graph states of systems with prime dimension. We construct protocols for three varieties of secret sharing: with classical and quantum secrets shared between parties over both classical and quantum channels.

  7. Flexible Layered Authentication Graph for Multimedia Streaming

    E-Print Network [OSTI]

    Sun, Qibin

    With the increasing demand on multimedia streaming in more and more applications, security issues such as integrity side, lost packets are dropped from the graph and a packet is verifiable if it has a path and all subsequent packets become not verifiable. EMSS [4] makes a great improvement by building multiple

  8. Lessons 6 Graphs of Functional Models

    E-Print Network [OSTI]

    2013-08-30T23:59:59.000Z

    Aug 30, 2013 ... One of the problems (#1) illustrates the principle of supply and demand, ... All of the problems involve building up a function model (see Lesson 5) ... Granite Management rents out several apartment complexes in the .... Side. 0.001 per cm2. Bottom. 0.005 per cm2. Lessons 6 Graphs of Functional Models.

  9. Line graphs e contrazioni: un approccio rigoroso alla space syntax

    E-Print Network [OSTI]

    D'Autilia, Roberto

    2015-01-01T23:59:59.000Z

    The methods of the space syntax have been the subject of extensive discussion, and several techniques to identify the axis lines have been proposed. The space syntax can be represented in terms of line graph, a graphs defined on the edge of a given primary graph. By means of the line graph algorithms, a system of labels defined on the edges of the primary graph is transformed into a system of labels on the vertices of the line graph. The contraction of adjacent edges with the same label allows to build a more general graph than those generated with the methods of the space syntax. By means of the functions implemented in Mathematica is therefore possible to redefine the space syntax on any system of urban quantities (labels) and reproduce the results of the axial lines as a special case. As an example is discussed a possible application of the method to the urban noise analysis.

  10. Data-flow graphs as a model of parallel complexity

    SciTech Connect (OSTI)

    Campbell, M.L.

    1987-01-01T23:59:59.000Z

    A new model of parallel computation based on data-flow graphs is introduced, which is specifically oriented towards complexity theory. Data-flow graphs are capable of illustrating properties of synchronous, asynchronous, and nondeterministic computations. Sufficient conditions are derived for asynchronous data-flow graphs to be determinate, i.e., all possible computations are finite and yield the same result. For determinate graphs, it is shown that the synchronous computation is as fast as any asynchronous computation. An algorithm is presented that transforms a nondeterminate data-flow graphs into a synchronous determinate one. The basic data-flow graph idea is extended into a model with greater potential parallelism, called the Uniform Data Flow Graph Family (UDFGF) Model. It is proved that time and space for the UDFGF model are polynomially related to reversal and space for the Turing Machine model, in both the deterministic and nondeterministic cases. In addition to forming an abstract computational model, data-flow graphs are parallel programs for real multiprocessors. Given a data flow graph program and a multiprocessor, each node of the graph must be assigned to one of the processors. It is proved that this problem is intractable, and a practical algorithm to find approximate solutions for it is presented.

  11. Crunching Large Graphs with Commodity Processors

    SciTech Connect (OSTI)

    Nelson, Jacob E.; Myers, Brandon D.; Hunter, Andrew H.; Briggs, Preston; Ceze, Luis; Ebeling, William C.; Grossman, Dan; Kahan, Simon H.; Oskin, Mark

    2011-05-26T23:59:59.000Z

    Crunching large graphs is the basis of many emerging appli- cations, such as social network analysis and bioinformatics. Graph analytics algorithms exhibit little locality and therefore present signi?cant performance challenges. Hardware multi- threading systems (e.g, Cray XMT) show that with enough concurrency, we can tolerate long latencies. Unfortunately, this solution is not available with commodity parts. Our goal is to develop a latency-tolerant system built out of commodity parts and mostly in software. The proposed system includes a runtime that supports a large number of lightweight contexts, full-bit synchronization and a memory manager that provides a high-latency but high-bandwidth global shared memory. This paper lays out the vision for our system, and justi?es its feasibility with a performance analysis of the run- time for latency tolerance.

  12. Local semicircle law for random regular graphs

    E-Print Network [OSTI]

    Roland Bauerschmidt; Antti Knowles; Horng-Tzer Yau

    2015-05-26T23:59:59.000Z

    We consider random $d$-regular graphs on $N$ vertices, with degree $d$ at least $(\\log N)^4$. We prove that the Green's function of the adjacency matrix and the Stieltjes transform of its empirical spectral measure are well approximated by Wigner's semicircle law, down to the optimal scale given by the typical eigenvalue spacing (up to a logarithmic correction). Aside from well-known consequences for the local eigenvalue distribution, this result implies the complete delocalization of all eigenvectors.

  13. Dynamics of entanglement of bosonic modes on symmetric graphs

    E-Print Network [OSTI]

    F. Ghahhari; V. Karimipour; R. Shahrokhshahi

    2006-11-23T23:59:59.000Z

    We investigate the dynamics of an initially disentangled Gaussian state on a general finite symmetric graph. As concrete examples we obtain properties of this dynamics on mean field graphs of arbitrary sizes. In the same way that chains can be used for transmitting entanglement by their natural dynamics, these graphs can be used to store entanglement. We also consider two kinds of regular polyhedron which show interesting features of entanglement sharing.

  14. k-Boson Quantum Walks Do Not Distinguish Arbitrary Graphs

    E-Print Network [OSTI]

    Jamie Smith

    2010-04-01T23:59:59.000Z

    In this paper, we define k-equivalence, a relation on graphs that relies on their associated cellular algebras. We show that a k-Boson quantum walk cannot distinguish pairs of graphs that are k- equivalent. The existence of pairs of k-equivalent graphs has been shown by Ponomarenko et al. [2, 6]. This gives a negative answer to a question posed by Gamble et al. [7].

  15. Nodal Parity Invariants of Knotted Rigid Vertex Graphs

    E-Print Network [OSTI]

    Kauffman, Louis H

    2012-01-01T23:59:59.000Z

    This paper introduces new invariants of rigid vertex graph embeddings by using non-local combinatorial information that is available at each graphical node. The new non-local information that we use in this paper involves parity in the Gauss code of the underlying graph. We apply these methods to graphs in classical and virtual knot theory, and we give formulations for applications to the topology of protein folding.

  16. An efficient semidefinite programming relaxation for the graph ...

    E-Print Network [OSTI]

    2012-08-28T23:59:59.000Z

    can be computed efficiently for larger graphs that have suitable algebraic symmetry. For a comparison of the SDP bounds for the GEP, see [45]. While the GEP is ...

  17. Generating Random Graphs with Large Girth Mohsen Bayati

    E-Print Network [OSTI]

    Montanari, Annamaria

    Generating Random Graphs with Large Girth Mohsen Bayati Andrea Montanari Amin Saberi Abstract We for Computational and Mathematical Engineering, Stanford University; saberi@stanford.edu. knowledge

  18. Graph searching and a generalized parking function

    E-Print Network [OSTI]

    Kostic, Dimitrije Nenad

    2009-05-15T23:59:59.000Z

    sequence (a1,a2,...,an) of non-negative integers for which there exists a permutation pi ?Sn such that 0 ?api(i) ?i?1 for all indexes i. In other words, if we choose a permutation pi such that api(1) ?api(2) ? ...? api(n) then we have (api(1),api(2),...,api... if at the end of this process we have removed all vertices from consideration. More formally, Proposition 7. A vertex function is a G-parking function if and only if there exists an ordering pi(1),pi(2),...,pi(n) of the vertices of a graph G such that for every...

  19. Visualization Graph | OpenEI Community

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directedAnnualProperty Edit withTianlin BaxinUmweltVillageGraph Home Wzeng's picture Submitted by Wzeng(50)

  20. Tables, Graphs, and Problems | ornl.gov

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengthening a solidSynthesis of 2D Alloys &8-5070P3. U.S.7.Tables, Graphs,

  1. Resource Minimized Static Mapping and Dynamic Scheduling of SDF Graphs

    E-Print Network [OSTI]

    Ha, Soonhoi

    Resource Minimized Static Mapping and Dynamic Scheduling of SDF Graphs Jinwoo Kim, Tae-ho Shin than the previous approaches. Keywords-Mapping, buffer size minimization, SDF graph, dynamic scheduling a model-based approach based on SDF (synchronous data flow) model. Since the parallelism of an application

  2. Synthesis of Parallel Hardware Implementations from Synchronous Dataflow Graph Specifications

    E-Print Network [OSTI]

    of automated register­transfer level (RTL) VHDL code generation from synchronous dataflow (SDF) graph for mapping applications specified in SDF to parallel digital hardware implementations. Two styles synthesis from SDF graphs is presented. In order to minimize cost while meeting performance require­ ments

  3. The Parallel BGL: A Generic Library for Distributed Graph Computations

    E-Print Network [OSTI]

    Lumsdaine, Andrew

    ] and written in a style similar to the C++ Standard Template Library (STL) [38, 46], 1 #12;data types providedThe Parallel BGL: A Generic Library for Distributed Graph Computations Douglas Gregor and Andrew,lums}@osl.iu.edu Abstract This paper presents the Parallel BGL, a generic C++ library for distributed graph computation

  4. Including Blind Students in Computer Science Through Access to Graphs

    E-Print Network [OSTI]

    Young, R. Michael

    Including Blind Students in Computer Science Through Access to Graphs Suzanne Balik, Sean Mealin SKetching tool, GSK, to provide blind and sighted people with a means to create, examine, and share graphs (node-link diagrams) in real-time. GSK proved very effective for one blind computer science student

  5. EvoGraphDice : Interactive Evolution for Visual Analytics

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    EvoGraphDice : Interactive Evolution for Visual Analytics Waldo Cancino, Nadia Boukhelifa, especially in frameworks like industrial design, decision making and visual analytics. Interactive Evolution visualization based on scatterplot matrices. EvoGraphDice interactively evolves com- pound additional dimensions

  6. Semidefinite programming and eigenvalue bounds for the graph ...

    E-Print Network [OSTI]

    2013-11-26T23:59:59.000Z

    Page 1 ... Using what we call the Laplacian algebra of a graph, we ..... Let us now consider graphs with symmetry, and assume that the data matrices of .... constraints (16) and (17) (respectively) don't occur precisely because of the vanishing of.

  7. Understanding Complex Network Attack Graphs through Clustered Adjacency Matrices

    E-Print Network [OSTI]

    Noel, Steven

    Understanding Complex Network Attack Graphs through Clustered Adjacency Matrices Steven Noel}@gmu.edu Abstract We apply adjacency matrix clustering to network attack graphs for attack correlation, prediction, and hypothesizing. We self-multiply the clustered adjacency matrices to show attacker reachability across

  8. Improving Attack Graph Visualization through Data Reduction and Attack Grouping

    SciTech Connect (OSTI)

    John Homer; Ashok Varikuti; Xinming Ou; Miles A. McQueen

    2008-09-01T23:59:59.000Z

    Various tools exist to analyze enterprise network systems and to produce attack graphs detailing how attackers might penetrate into the system. These attack graphs, however, are often complex and difficult to comprehend fully, and a human user may find it problematic to reach appropriate configuration decisions. This paper presents methodologies that can 1) automatically identify portions of an attack graph that do not help a user to understand the core security problems and so can be trimmed, and 2) automatically group similar attack steps as virtual nodes in a model of the network topology, to immediately increase the understandability of the data. We believe both methods are important steps toward improving visualization of attack graphs to make them more useful in configuration management for large enterprise networks. We implemented our methods using one of the existing attack-graph toolkits. Initial experimentation shows that the proposed approaches can 1) significantly reduce the complexity of attack graphs by trimming a large portion of the graph that is not needed for a user to understand the security problem, and 2) significantly increase the accessibility and understandability of the data presented in the attack graph by clearly showing, within a generated visualization of the network topology, the number and type of potential attacks to which each host is exposed.

  9. Math 304 Handout: Linear algebra, graphs, and networks.

    E-Print Network [OSTI]

    Anshelevich, Michael

    and adjacency matrices. 1 2. Word search 3 3. Ranking the web pages. 4 1. GRAPHS AND ADJACENCY MATRICES. · The World Wide Web is a directed graph, with web pages as vertices and links as edges. · Towns connected column corresponds to a web page, each row to a word, and each entry is 1 if a particular word occurs

  10. Analogical Representation and Graph Comprehension Aidan Feeney and Lara Webber

    E-Print Network [OSTI]

    comprehension make the assumption that viewers build up a wholly propositional description of the graph a scale of two different levels of a variable, one may extract information about the value of each level with the information presented in the graph. A is high on the scale B is low on the scale A is higher on the scale than

  11. The Generic Graph Component Library Dr. Dobb's Journal September 2000

    E-Print Network [OSTI]

    Lumsdaine, Andrew

    .nd.edu, and lumsg@lsc.nd.edu, respectively. The Standard Template Library has established a solid foundation generic programming has to offer. In January, 1999, we did a survey of existing graph libraries. Some.mpi-sb.mpg.de/LEDA/leda.html), the Graph Template Library (GTL) (by Michael Forster, Andreas Pick, and Marcus Raitner, http

  12. On the concurrent semantics of Algebraic Graph Grammars #

    E-Print Network [OSTI]

    Baldan, Paolo

    â??a di Pisa, Italy baldan@dsi.unive.it andrea@di.unipi.it Abstract. Graph grammars are a powerful model. These semantics have served as basis for the development of a variety of modelling and verification techniques graph transformation systems as an alternative model of concurrency, extending Petri nets. The basic

  13. Power Domination in Cylinders, Tori, and Generalized Petersen Graphs

    E-Print Network [OSTI]

    Ferrero, Daniela - Department of Mathematics, Texas State University

    of graphs by Haynes et al. in 2002 [7]. Indeed, an electrical power network can be modeled by a graph where for power system monitoring. The minimum cardi- nality of a PDS of G is its power domination number. INTRODUCTION Electric power companies need to monitor the state of their networks continually. The state

  14. Hierarchical Remote Sensing Image Analysis via Graph Laplacian Energy

    E-Print Network [OSTI]

    Zhou, Jun

    1 Hierarchical Remote Sensing Image Analysis via Graph Laplacian Energy Zhang Huigang, Bai Xiao for an efficient image description, which may cause increased computational complexity. In this paper, we propose a new hierarchical segmentation method that applies graph Laplacian energy as a generic measure

  15. SPATIAL POINT PROCESSES AND GRAPH BASED STATISTICAL FEATURES

    E-Print Network [OSTI]

    Jyväskylä, University of

    2010 2000 Mathematics Subject Classification. 60G55, 62-07, 62M30. ISSN 1457-9235 #12;SPATIAL POINT Classification. 60G55, 62-07, 62M30. 1 #12;Spatial point processes and graph based statistical features Tuomas library has been developed for the computation of the graph-based summaries. Keywords: Spatial point

  16. Scaling Semantic Graph Databases in Size and Performance

    SciTech Connect (OSTI)

    Morari, Alessandro; Castellana, Vito G.; Villa, Oreste; Tumeo, Antonino; Weaver, Jesse R.; Haglin, David J.; Choudhury, Sutanay; Feo, John T.

    2014-08-06T23:59:59.000Z

    In this paper we present SGEM, a full software system for accelerating large-scale semantic graph databases on commodity clusters. Unlike current approaches, SGEM addresses semantic graph databases by only employing graph methods at all the levels of the stack. On one hand, this allows exploiting the space efficiency of graph data structures and the inherent parallelism of graph algorithms. These features adapt well to the increasing system memory and core counts of modern commodity clusters. On the other hand, however, these systems are optimized for regular computation and batched data transfers, while graph methods usually are irregular and generate fine-grained data accesses with poor spatial and temporal locality. Our framework comprises a SPARQL to data parallel C compiler, a library of parallel graph methods and a custom, multithreaded runtime system. We introduce our stack, motivate its advantages with respect to other solutions and show how we solved the challenges posed by irregular behaviors. We present the result of our software stack on the Berlin SPARQL benchmarks with datasets up to 10 billion triples (a triple corresponds to a graph edge), demonstrating scaling in dataset size and in performance as more nodes are added to the cluster.

  17. Deciding Timed Bisimulation for Timed Automata Using Zone Valuation Graph

    E-Print Network [OSTI]

    Prasad, Sanjiva

    Deciding Timed Bisimulation for Timed Automata Using Zone Valuation Graph Shibashis Guha, Chinmay was first proved to be decidable for timed automata by Cerans using a product construction method on region graph. Several other methods have been proposed in the literature since then for decid- ing timed

  18. Scalability Analysis of Partitioning Strategies for Finite Element Graphs. \\Lambda

    E-Print Network [OSTI]

    Kumar, Vipin

    Scalability Analysis of Partitioning Strategies for Finite Element Graphs. \\Lambda Grama Y. Ananth Y. Grama ananth@cs:umn:edu Abstract Issues of partitioning Finite Element Graphs are central for implementing the Finite Element Method (FEM). Parallel formulations of finite element techniques require

  19. A Surface Reconstruction Method Using Global Graph Cut Optimization

    E-Print Network [OSTI]

    Paris, Sylvain

    SAR (China) 1 sparis@csail.mit.edu -- Sylvain Paris has worked on this project during his PhD at ARTIS calibrated images mainly has been approached using local methods, either as a continuous optimization problem of a pixel. Index Terms Graph flow, graph cut, 3D reconstruction from calibrated cameras, discontinuities

  20. A Surface Reconstruction Method Using Global Graph Cut Optimization

    E-Print Network [OSTI]

    Paris, Sylvain

    SAR (China) 1sparis@csail.mit.edu ­ Sylvain Paris has worked on this project during his PhD at ARTIS calibrated images mainly has been approached using local methods, either as a continuous optimization problem of a pixel. Index Terms Graph flow, graph cut, 3D reconstruction from calibrated cameras, discontinuities

  1. A Surface Reconstruction Method Using Global Graph Cut Optimization

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    SAR (China) 1sparis@csail.mit.edu ­ Sylvain Paris has worked on this project during his PhD at ARTIS reconstruction from multiple calibrated images mainly has been approached using local methods, either to 1/10th of a pixel. Index Terms Graph flow, graph cut, 3D reconstruction from calibrated cameras

  2. Video Denoising and Simplification Via Discrete Regularization on Graphs

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Video Denoising and Simplification Via Discrete Regularization on Graphs Mahmoud Ghoniem, Youssef algorithms for video de- noising and simplification based on discrete regularization on graphs. The main difference between video and image denoising is the temporal redundancy in video sequences. Recent works

  3. VIDEO SUMMARIZATION BY VIDEO STRUCTURE ANALYSIS AND GRAPH OPTIMIZATION

    E-Print Network [OSTI]

    King, Kuo Chin Irwin

    VIDEO SUMMARIZATION BY VIDEO STRUCTURE ANALYSIS AND GRAPH OPTIMIZATION Shi Lu, Irwin King video summarization method that combines video structure analysis and graph optimiza- tion. First, we analyze the structure of the video, find the boundaries of video scenes, then we calculate each scene

  4. Albert R Meyer April 1, 2013 sexgraph.1 Graph Theory

    E-Print Network [OSTI]

    Meyer, Albert R.

    1 Albert R Meyer April 1, 2013 sexgraph.1 Graph Theory & Sex Albert R Meyer April 1, 2013 sexgraph women partners Albert R Meyer April 1, 2013 sexgraph.3 Sex in America: Men more Promiscuous? Studies this is nonsense Albert R Meyer April 1, 2013 sexgraph.4 M partners F Sex Partner Graph #12;2 Albert R Meyer April

  5. An Introduction to Game Trees Ross Casebolt --Graph Theory

    E-Print Network [OSTI]

    Laison, Josh

    Ross Casebolt -- Graph Theory Lobsters vs Caterpillars! #12;What is a game? Definition (Game) A game G Theory Lobsters vs Caterpillars! #12;What is a game? Definition (Game) A game G must satisfy Ross Casebolt -- Graph Theory Lobsters vs Caterpillars! #12;What is a game? Definition (Game) A game G

  6. International energy indicators. [Statistical tables and graphs

    SciTech Connect (OSTI)

    Bauer, E.K. (ed.)

    1980-05-01T23:59:59.000Z

    International statistical tables and graphs are given for the following: (1) Iran - Crude Oil Capacity, Production and Shut-in, June 1974-April 1980; (2) Saudi Arabia - Crude Oil Capacity, Production, and Shut-in, March 1974-Apr 1980; (3) OPEC (Ex-Iran and Saudi Arabia) - Capacity, Production and Shut-in, June 1974-March 1980; (4) Non-OPEC Free World and US Production of Crude Oil, January 1973-February 1980; (5) Oil Stocks - Free World, US, Japan, and Europe (Landed, 1973-1st Quarter, 1980); (6) Petroleum Consumption by Industrial Countries, January 1973-December 1979; (7) USSR Crude Oil Production and Exports, January 1974-April 1980; and (8) Free World and US Nuclear Generation Capacity, January 1973-March 1980. Similar statistical tables and graphs included for the United States include: (1) Imports of Crude Oil and Products, January 1973-April 1980; (2) Landed Cost of Saudi Oil in Current and 1974 Dollars, April 1974-January 1980; (3) US Trade in Coal, January 1973-March 1980; (4) Summary of US Merchandise Trade, 1976-March 1980; and (5) US Energy/GNP Ratio, 1947 to 1979.

  7. Noisy entanglement evolution for graph states

    E-Print Network [OSTI]

    L. Aolita; D. Cavalcanti; R. Chaves; C. Dhara; L. Davidovich; A. Acin

    2011-03-29T23:59:59.000Z

    A general method for the study of the entanglement evolution of graph states under the action of Pauli was recently proposed in [Cavalcanti, et al., Phys. Rev. Lett. 103, 030502 (2009)]. This method is based on lower and upper bounds on the entanglement of the entire state as a function only of the state of a considerably-smaller subsystem, which undergoes an effective noise process. This provides a huge simplification on the size of the matrices involved in the calculation of entanglement in these systems. In the present paper we elaborate on this method in details and generalize it to other natural situations not described by Pauli maps. Specifically, for Pauli maps we introduce an explicit formula for the characterization of the resulting effective noise. Beyond Pauli maps, we show that the same ideas can be applied to the case of thermal reservoirs at arbitrary temperature. In the latter case, we discuss how to optimize the bounds as a function of the noise strength. We illustrate our ideas with explicit exemplary results for several different graphs and particular decoherence processes. The limitations of the method are also discussed.

  8. Embeddings of Cubic Halin Graphs A Surface-by-Surface Inventory

    E-Print Network [OSTI]

    Gross, Jonathan L.

    Embeddings of Cubic Halin Graphs A Surface-by-Surface Inventory Jonathan L. Gross Columbia@cs.columbia.edu; http://www.cs.columbia.edu/gross/. 1 #12;Embeddings of Cubic Halin Graphs: An Inventory 2 1 graph for a 14-vertex tree with 8 leaves. #12;Embeddings of Cubic Halin Graphs: An Inventory 3

  9. Interactive Visualization of Genealogical Graphs Michael J. McGuffin Ravin Balakrishnan

    E-Print Network [OSTI]

    McGuffin, Michael J.

    Interactive Visualization of Genealogical Graphs Michael J. McGuffin Ravin Balakrishnan Department of visualizing "family trees", or genealogi- cal graphs, in 2D, is considered. A graph theoretic analysis is given, which identifies why genealogical graphs can be difficult to draw. This motivates some novel

  10. NPDA Transition Graphs To understand NPDAs, it is useful to have a visual representation. This

    E-Print Network [OSTI]

    Bylander, Tom

    NPDA Transition Graphs To understand NPDAs, it is useful to have a visual representation. This document introduces NPDA transition graphs. This type of graph extends the notation for DFA/NFA transition Edition, Addison-Wesley, 2001. In a DFA/NFA transition graph, there is an edge from vertex qi to vertex qj

  11. Energy Models for Drawing Signed Graphs Anne-Marie Kermarrec and Afshin Moin

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    by proposing a dual energy model for graphs containing uniquely negative edges, and combining it linearly

  12. The elliptic dilogarithm for the sunset graph

    E-Print Network [OSTI]

    Spencer Bloch; Pierre Vanhove

    2014-10-24T23:59:59.000Z

    We study the sunset graph defined as the scalar two-point self-energy at two-loop order. We evaluate the sunset integral for all identical internal masses in two dimensions. We give two calculations for the sunset amplitude; one based on an interpretation of the amplitude as an inhomogeneous solution of a classical Picard-Fuchs differential equation, and the other using arithmetic algebraic geometry, motivic cohomology, and Eisenstein series. Both methods use the rather special fact that the amplitude in this case is a family of periods associated to the universal family of elliptic curves over the modular curve X_1(6). We show that the integral is given by an elliptic dilogarithm evaluated at a sixth root of unity modulo periods. We explain as well how this elliptic dilogarithm value is related to the regulator of a class in the motivic cohomology of the universal elliptic family.

  13. Well performance graph simplifies field calculations

    SciTech Connect (OSTI)

    De Ghetto, G.

    1987-05-01T23:59:59.000Z

    Graphic Methods are widely employed in order to understand overall well behavior using only surface parameters. The authors propose a new graphic method, used successfully by Agip for oil and gas wells in Italy, Libya, Nigeria and Tunisia. The well performance graph helps solve many production problems, including estimation of: inflow performance relationship; causes of rate decline throughout well life; and production rate and bottomhole flowing pressure for various pressures upstream of the surface choke, and vice-versa. This method differs from others by using flow behavior through the choke for both critical and subcritical conditions. Equations describing flow through the formation, string and surface choke are also used. Results are quite reliable when these theoretical equations are calibrated with field data, either from the well concerned or from nearby wells producing the same fluid. This article describes the technique as it applies to oil wells. The methodology for gas wells is similar.

  14. Community detection in directed acyclic graphs

    E-Print Network [OSTI]

    Speidel, Leo; Masuda, Naoki

    2015-01-01T23:59:59.000Z

    Some temporal networks, most notably citation networks, are naturally represented as directed acyclic graphs (DAGs). To detect communities in DAGs, we propose a modularity for DAGs by defining an appropriate null model (i.e., randomized network) respecting the order of nodes. We implement a spectral method to approximately maximize the proposed modularity measure and test the method on citation networks and other DAGs. We find that the attained values of the modularity for DAGs are similar for partitions that we obtain by maximizing the proposed modularity (designed for DAGs), the modularity for undirected networks and that for general directed networks. In other words, if we neglect the order imposed on nodes (and the direction of links) in a given DAG and maximize the conventional modularity measure, the obtained partition is close to the optimal one in the sense of the modularity for DAGs.

  15. The Graph Laplacian and the Dynamics of Complex Networks

    SciTech Connect (OSTI)

    Thulasidasan, Sunil [Los Alamos National Laboratory

    2012-06-11T23:59:59.000Z

    In this talk, we explore the structure of networks from a spectral graph-theoretic perspective by analyzing the properties of the Laplacian matrix associated with the graph induced by a network. We will see how the eigenvalues of the graph Laplacian relate to the underlying network structure and dynamics and provides insight into a phenomenon frequently observed in real world networks - the emergence of collective behavior from purely local interactions seen in the coordinated motion of animals and phase transitions in biological networks, to name a few.

  16. Computing the stability number of a graph via semidefinite and ...

    E-Print Network [OSTI]

    2006-04-27T23:59:59.000Z

    then the vertices of G can be numbered so that E(G8) ? E(G ). Thus G8 is the smallest graph G such that ?(1)(G) > ?(G) = 3. We can extend the above reasoning ...

  17. Min-Max Theorems Related to Geometric Representationsof Graphs ...

    E-Print Network [OSTI]

    Marcel K. de Carli Silva and Levent Tuncel

    2011-08-06T23:59:59.000Z

    Oct 27, 2010 ... 1. Introduction. Geometric representations of graphs is a beautiful area where combina- ..... We shall use the following construction to get hypersphere ...... This is not surprising, as SDP duality theory is more complex than LP.

  18. Poster: -Graphs: Flexible Topology Control in Wireless Ad Hoc Networks

    E-Print Network [OSTI]

    Williamson, Carey

    Poster: -Graphs: Flexible Topology Control in Wireless Ad Hoc Networks Ashikur Rahman Department networks. Most algorithms strive to reduce energy consumption by cre- ating a sparse topology with few long of topologies and provides the flexibility to network

  19. The competition number of a graph with exactly two holes

    E-Print Network [OSTI]

    ] as a means of deter- mining the smallest dimension of ecological phase space. Since then, various variations to ecology, the concept of competition graph can be applied to a variety of fields, as summarized in [11

  20. The competition number of a graph with exactly two holes

    E-Print Network [OSTI]

    ] as a means of deter­ mining the smallest dimension of ecological phase space. Since then, various variations to ecology, the concept of competition graph can be applied to a variety of fields, as summarized in [11

  1. Decoding linear codes via optimization and graph-based techniques

    E-Print Network [OSTI]

    Taghavi, Mohammad H.

    2008-01-01T23:59:59.000Z

    2.2.1 Linear Codes on1.1.2 Graph-Based Codes 1.2 Dissertation Overview . . .versus the length of the code for (3,6)-regular LDPC codes (

  2. MacWilliams identities for codes on graphs

    E-Print Network [OSTI]

    Forney, G. David, Jr.

    The MacWilliams identity for linear time-invariant convolutional codes that has recently been found by Gluesing-Luerssen and Schneider is proved concisely, and generalized to arbitrary group codes on graphs. A similar ...

  3. Technology Portfolio Planning by Weighted Graph Analysis of System Architectures

    E-Print Network [OSTI]

    de Weck, Olivier L.

    Technology Portfolio Planning by Weighted Graph Analysis of System Architectures Peter Davison and Bruce Cameron Massachusetts Institute of Technology, Cambridge, MA 02139 Edward F. Crawley Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia Abstract5 Many systems undergo significant

  4. The Asymmetric Traveling Salesman Problem on Graphs with Bounded Genus

    E-Print Network [OSTI]

    Saberi, Amin

    Saberi Abstract We give a constant factor approximation algorithm for the asymmetric traveling salesman:{shayan, saberi}@stanford.edu. 1 #12;Thin trees were first defined in the graph embedding literature in an attempt

  5. Random Walks with Lookahead in Power Law Random Graphs

    E-Print Network [OSTI]

    Mihail, Milena

    1 Random Walks with Lookahead in Power Law Random Graphs Milena Mihail Amin Saberi Prasad Tetali Georgia Institute of Technology Email: mihail, saberi¡ @cc.gatech.edu tetali@math.cc.gatech.edu Abstract

  6. Confluence in Data Reduction: Bridging Graph Transformation and Kernelization

    E-Print Network [OSTI]

    Wichmann, Felix

    Ermel Falk H¨uffner Rolf Niedermeier Olga Runge Institut f¨ur Softwaretechnik und Theoretische of critical pair analysis from graph transformation theory, supported by the AGG software tool. These results

  7. Advanced Vulnerability Analysis and Intrusion Detection Through Predictive Attack Graphs

    E-Print Network [OSTI]

    Noel, Steven

    Advanced Vulnerability Analysis and Intrusion Detection Through Predictive Attack Graphs Steven, without considering how they contribute to overall attack risk. Similarly, intrusion alarms are logged threats, complexity of security data, and network growth. Our approach to network defense applies attack

  8. Modeling modern network attacks and countermeasures using attack graphs

    E-Print Network [OSTI]

    Ingols, Kyle W.

    By accurately measuring risk for enterprise networks, attack graphs allow network defenders to understand the most critical threats and select the most effective countermeasures. This paper describes substantial enhancements ...

  9. Fracture and Fragmentation of Simplicial Finite Elements Meshes using Graphs

    SciTech Connect (OSTI)

    Mota, A; Knap, J; Ortiz, M

    2006-10-18T23:59:59.000Z

    An approach for the topological representation of simplicial finite element meshes as graphs is presented. It is shown that by using a graph, the topological changes induced by fracture reduce to a few, local kernel operations. The performance of the graph representation is demonstrated and analyzed, using as reference the 3D fracture algorithm by Pandolfi and Ortiz [22]. It is shown that the graph representation initializes in O(N{sub E}{sup 1.1}) time and fractures in O(N{sub I}{sup 1.0}) time, while the reference implementation requires O(N{sub E}{sup 2.1}) time to initialize and O(N{sub I}{sup 1.9}) time to fracture, where NE is the number of elements in the mesh and N{sub I} is the number of interfaces to fracture.

  10. Ranking Outlier Nodes in Subspaces of Attributed Graphs

    E-Print Network [OSTI]

    Antwerpen, Universiteit

    . Our graph outlier ranking (GOutRank) introduces scoring functions based on these selected subgraphs by looking at the most promising objects first. They 1http://www.ipd.kit.edu/~muellere/GOutRank/ allow users

  11. Finding structural anomalies in graphs by means of quantum walks

    SciTech Connect (OSTI)

    Feldman, Edgar [Department of Mathematics, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, New York 10016 (United States); Hillery, Mark; Zheng, Hongjun [Department of Physics, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10021 (United States); Lee, Hai-Woong [Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Reitzner, Daniel; Buzek, Vladimir [Research Center for Quantum Information, Slovak Academy of Sciences, Dubravska cesta 9, 845 11 Bratislava (Slovakia)

    2010-10-15T23:59:59.000Z

    We explore the possibility of using quantum walks on graphs to find structural anomalies, such as extra edges or loops, on a graph. We focus our attention on star graphs, whose edges are like spokes coming out of a central hub. If there are N spokes, we show that a quantum walk can find an extra edge connecting two of the spokes or a spoke with a loop on it in O({radical}(N)) steps. We initially find that if all except one of the spokes have loops, the walk will not find the spoke without a loop, but this can be fixed if we choose the phase with which the particle is reflected from the vertex without the loop. Consequently, quantum walks can, under some circumstances, be used to find structural anomalies in graphs.

  12. Checking and Comparison of WB-Graphs Peter B. Ladkin

    E-Print Network [OSTI]

    Ladkin, Peter B.

    as a running comparison. These graphs were produced by beginners at WBA, namely students in the first semester. It also caused the trauma death of the co-pilot, as well as the loss of consciousness of a passenger, who

  13. Local computation algorithms for graphs of non-constant degrees

    E-Print Network [OSTI]

    Yodpinyanee, Anak

    2014-01-01T23:59:59.000Z

    In the model of local computation algorithms (LCAs), we aim to compute the queried part of the output by examining only a small (sublinear) portion of the input. Many recently developed LCAs on graph problems achieve time ...

  14. Circuit and bond polytopes on series-parallel graphs$

    E-Print Network [OSTI]

    2014-07-10T23:59:59.000Z

    Jul 10, 2014 ... If G is a non trivial 2-connected series-parallel graph, an open nested ear decomposition ... no interior point of an ear Ei belongs to Ej for all j < i,.

  15. Stirling numbers of graphs, and the normal ordering

    E-Print Network [OSTI]

    Mayfield, John

    Stirling numbers of graphs, and the normal ordering problem Galvin earned his PhD in mathematics correlations in discrete random structures. The Stirling number of the second kind ${n \\brace k}$ counts

  16. On the limiting absorption principle and spectra of quantum graphs

    E-Print Network [OSTI]

    Beng-Seong Ong

    2005-10-10T23:59:59.000Z

    The main result of the article is validity of the limiting absorption principle and thus absence of the singular continuous spectrum for compact quantum graphs with several infinite leads attached. The technique used involves Dirichlet-to-Neumann operators.

  17. Discrete Mathematics and Theoretical Computer Science DMTCS vol. 11:2, 2009, 149160 Spectral characterizations of sun graphs and

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    characterizations of sun graphs and broken sun graphs Romain Boulet Institut de Math´ematiques de Toulouse by their spectrum by considering some unicyclic graphs. An odd (resp. even) sun is a graph obtained by appending a pendant vertex to each vertex of an odd (resp. even) cycle. A broken sun is a graph obtained by deleting

  18. Noisy entanglement evolution for graph states

    E-Print Network [OSTI]

    Aolita, L; Chaves, R; Dhara, C; Davidovich, L; Acin, A

    2010-01-01T23:59:59.000Z

    A general method for the study of the entanglement evolution of graph states under the action of Pauli was recently proposed in [Cavalcanti, et al., Phys. Rev. Lett. 103, 030502 (2009)]. This method is based on lower and upper bounds on the entanglement of the entire state as a function only of the state of a considerably-smaller subsystem, which undergoes an effective noise process. This provides a huge simplification on the size of the matrices involved in the calculation of entanglement in these systems. In the present paper we elaborate on this method in details and generalize it to other natural situations not described by Pauli maps. Specifically, for Pauli maps we introduce an explicit formula for the characterization of the resulting effective noise. Beyond Pauli maps, we show that the same ideas can be applied to the case of thermal reservoirs at arbitrary temperature. In the latter case, we discuss how to optimize the bounds as a function of the noise strength. We illustrate our ideas with explicit ...

  19. Quantum Vacuum Energy in Graphs and Billiards

    E-Print Network [OSTI]

    L. Kaplan

    2011-01-03T23:59:59.000Z

    The vacuum (Casimir) energy in quantum field theory is a problem relevant both to new nanotechnology devices and to dark energy in cosmology. The crucial question is the dependence of the energy on the system geometry under study. Despite much progress since the first prediction of the Casimir effect in 1948 and its subsequent experimental verification in simple geometries, even the sign of the force in nontrivial situations is still a matter of controversy. Mathematically, vacuum energy fits squarely into the spectral theory of second-order self-adjoint elliptic linear differential operators. Specifically, one promising approach is based on the small-t asymptotics of the cylinder kernel e^(-t sqrt(H)), where H is the self-adjoint operator under study. In contrast with the well-studied heat kernel e^(-tH), the cylinder kernel depends in a non-local way on the geometry of the problem. We discuss some results by the Louisiana-Oklahoma-Texas collaboration on vacuum energy in model systems, including quantum graphs and two-dimensional cavities. The results may shed light on general questions, including the relationship between vacuum energy and periodic or closed classical orbits, and the contribution to vacuum energy of boundaries, edges, and corners.

  20. Experimental entanglement of six photons in graph states

    E-Print Network [OSTI]

    Chao-Yang Lu; Xiao-Qi Zhou; Otfried Gühne; Wei-Bo Gao; Jin Zhang; Zhen-Sheng Yuan; Alexander Goebel; Tao Yang; Jian-Wei Pan

    2006-09-18T23:59:59.000Z

    Graph states are special kinds of multipartite entangled states that correspond to mathematical graphs where the vertices take the role of quantum spin systems and the edges represent interactions. They not only provide an efficient model to study multiparticle entanglement, but also find wide applications in quantum error correction, multi-party quantum communication and most prominently, serve as the central resource in one-way quantum computation. Here we report the creation of two special instances of graph states, the six-photon Greenberger-Horne-Zeilinger states -- the largest photonic Schr\\"{o}dinger cat, and the six-photon cluster states-- a state-of-the-art one-way quantum computer. Flexibly, slight modifications of our method allow creation of many other graph states. Thus we have demonstrated the ability of entangling six photons and engineering multiqubit graph states, and created a test-bed for investigations of one-way quantum computation and studies of multiparticle entanglement as well as foundational issues such as nonlocality and decoherence.

  1. A graph-based system for network-vulnerability analysis

    SciTech Connect (OSTI)

    Swiler, L.P.; Phillips, C.

    1998-06-01T23:59:59.000Z

    This paper presents a graph-based approach to network vulnerability analysis. The method is flexible, allowing analysis of attacks from both outside and inside the network. It can analyze risks to a specific network asset, or examine the universe of possible consequences following a successful attack. The graph-based tool can identify the set of attack paths that have a high probability of success (or a low effort cost) for the attacker. The system could be used to test the effectiveness of making configuration changes, implementing an intrusion detection system, etc. The analysis system requires as input a database of common attacks, broken into atomic steps, specific network configuration and topology information, and an attacker profile. The attack information is matched with the network configuration information and an attacker profile to create a superset attack graph. Nodes identify a stage of attack, for example the class of machines the attacker has accessed and the user privilege level he or she has compromised. The arcs in the attack graph represent attacks or stages of attacks. By assigning probabilities of success on the arcs or costs representing level-of-effort for the attacker, various graph algorithms such as shortest-path algorithms can identify the attack paths with the highest probability of success.

  2. Random intersection graphs and their applications in security, wireless communication, and social networks

    E-Print Network [OSTI]

    Zhao, Jun; Gligor, Virgil

    2015-01-01T23:59:59.000Z

    Random intersection graphs have received much interest and been used in diverse applications. They are naturally induced in modeling secure sensor networks under random key predistribution schemes, as well as in modeling the topologies of social networks including common-interest networks, collaboration networks, and actor networks. Simply put, a random intersection graph is constructed by assigning each node a set of items in some random manner and then putting an edge between any two nodes that share a certain number of items. Broadly speaking, our work is about analyzing random intersection graphs, and models generated by composing it with other random graph models including random geometric graphs and Erd\\H{o}s-R\\'enyi graphs. These compositional models are introduced to capture the characteristics of various complex natural or man-made networks more accurately than the existing models in the literature. For random intersection graphs and their compositions with other random graphs, we study properties su...

  3. Semi-classical measures on Quantum graphs and the Gau map of the determinant manifold

    E-Print Network [OSTI]

    Recanati, Catherine

    believed that QE does not hold in general for a FIXED quantum graph. This is proved for star graphs in [BKW to what people do in several papers like [BG00, BKW04, BW08, Ba12, BB13]. Let

  4. Math 497E/564 Graph Theory Winter 2012 Instructor Amites Sarkar

    E-Print Network [OSTI]

    Sarkar, Amites

    Math 497E/564 Graph Theory Winter 2012 Instructor Amites Sarkar Text Modern Graph Theory B, in 216 Bond Hall. My phone number is 650 7569 and my e-mail is amites.sarkar@wwu.edu #12;

  5. Fast Search for Dynamic Multi-Relational Graphs

    SciTech Connect (OSTI)

    Choudhury, Sutanay; Holder, Larry; Chin, George; Feo, John T.

    2013-06-23T23:59:59.000Z

    Acting on time-critical events by processing ever growing social media or news streams is a major technical challenge. Many of these data sources can be modeled as multi-relational graphs. Continuous queries or techniques to search for rare events that typically arise in monitoring applications have been studied extensively for relational databases. This work is dedicated to answer the question that emerges naturally: how can we efficiently execute a continuous query on a dynamic graph? This paper presents an exact subgraph search algorithm that exploits the temporal characteristics of representative queries for online news or social media monitoring. The algorithm is based on a novel data structure called the that leverages the structural and semantic characteristics of the underlying multi-relational graph. The paper concludes with extensive experimentation on several real-world datasets that demonstrates the validity of this approach.

  6. Asymptotic structure and singularities in constrained directed graphs

    E-Print Network [OSTI]

    David Aristoff; Lingjiong Zhu

    2015-02-17T23:59:59.000Z

    We study the asymptotics of large directed graphs, constrained to have certain densities of edges and/or outward $p$-stars. Our models are close cousins of exponential random graph models (ERGMs), in which edges and certain other subgraph densities are controlled by parameters. The idea of directly constraining edge and other subgraph densities comes from Radin and Sadun. Such modeling circumvents a phenomenon first made precise by Chatterjee and Diaconis: that in ERGMs it is often impossible to independently constrain edge and other subgraph densities. In all our models, we find that large graphs have either uniform or bipodal structure. When edge density (resp. $p$-star density) is fixed and $p$-star density (resp. edge density) is controlled by a parameter, we find phase transitions corresponding to a change from uniform to bipodal structure. When both edge and $p$-star density are fixed, we find only bipodal structures and no phase transition.

  7. Regular graphs maximize the variability of random neural networks

    E-Print Network [OSTI]

    Gilles Wainrib; Mathieu Galtier

    2014-12-17T23:59:59.000Z

    In this work we study the dynamics of systems composed of numerous interacting elements interconnected through a random weighted directed graph, such as models of random neural networks. We develop an original theoretical approach based on a combination of a classical mean-field theory originally developed in the context of dynamical spin-glass models, and the heterogeneous mean-field theory developed to study epidemic propagation on graphs. Our main result is that, surprisingly, increasing the variance of the in-degree distribution does not result in a more variable dynamical behavior, but on the contrary that the most variable behaviors are obtained in the regular graph setting. We further study how the dynamical complexity of the attractors is influenced by the statistical properties of the in-degree distribution.

  8. An improved spectral graph partitioning algorithm for mapping parallel computations

    SciTech Connect (OSTI)

    Hendrickson, B.; Leland, R.

    1992-09-01T23:59:59.000Z

    Efficient use of a distributed memory parallel computer requires that the computational load be balanced across processors in a way that minimizes interprocessor communication. We present a new domain mapping algorithm that extends recent work in which ideas from spectral graph theory have been applied to this problem. Our generalization of spectral graph bisection involves a novel use of multiple eigenvectors to allow for division of a computation into four or eight parts at each stage of a recursive decomposition. The resulting method is suitable for scientific computations like irregular finite elements or differences performed on hypercube or mesh architecture machines. Experimental results confirm that the new method provides better decompositions arrived at more economically and robustly than with previous spectral methods. We have also improved upon the known spectral lower bound for graph bisection.

  9. Metric intersection problems in Cayley graphs and the Stirling recursion

    E-Print Network [OSTI]

    Phongpattanacharoen, Teeraphong

    2012-01-01T23:59:59.000Z

    In the symmetric group Sym(n) with n at least 5 let H be a conjugacy class of elements of order 2 and let \\Gamma be the Cayley graph whose vertex set is the group G generated by H (so G is Sym(n) or Alt(n)) and whose edge set is determined by H. We are interested in the metric structure of this graph. In particular, for g\\in G let B_{r}(g) be the metric ball in \\Gamma of radius r and centre g. We show that the intersection numbers \\Phi(\\Gamma; r, g):=|\\,B_{r}(e)\\,\\cap\\,B_{r}(g)\\,| are generalized Stirling functions in n and r. The results are motivated by the study of error graphs and related reconstruction problems.

  10. Graph Applications To know the Seven Bridges of Knigsberg problem and

    E-Print Network [OSTI]

    Liang, Y. Daniel

    the shortest distance between two cities can be modeled using a graph, where the vertices represent cities

  11. Handling Context-Sensitivity in Protein Structures Using Graph Theory: Bona Fide Prediction

    E-Print Network [OSTI]

    Samudrala, Ram

    structure(s).5 METHODS General Description of the Graph-Theoretic Clique-Finding Approach Each possible

  12. Exercise 1: part 1 p Consider the simple web graph shown in slide 72

    E-Print Network [OSTI]

    Ricci, Francesco

    the file and brose the content of the class directory p Transform the input graphs tiny.txt and medium

  13. Approximate Graph Coloring by Semidefinite Programming David Karger \\Lambda Rajeev Motwani y Madhu Sudan z

    E-Print Network [OSTI]

    Sudan z Abstract We consider the problem of coloring k­colorable graphs with the fewest possible colors

  14. Highly Connected Random Geometric Graphs Paul Balister #+ Bela Bollobas +# Amites Sarkar + Mark Walters #

    E-Print Network [OSTI]

    Banaji,. Murad

    Highly Connected Random Geometric Graphs Paul Balister #+ Bâ??ela Bollobâ??as +#§ Amites Sarkar +¶ Mark

  15. A Structure Theory of the Sandpile Monoid for Directed Graphs Laszlo Babai

    E-Print Network [OSTI]

    Babai, László

    A Structure Theory of the Sandpile Monoid for Directed Graphs L´aszl´o Babai Evelin Toumpakari June

  16. Bounds for mixing time of quantum walks on finite graphs

    E-Print Network [OSTI]

    Vladislav Kargin

    2010-07-21T23:59:59.000Z

    Several inequalities are proved for the mixing time of discrete-time quantum walks on finite graphs. The mixing time is defined differently than in Aharonov, Ambainis, Kempe and Vazirani (2001) and it is found that for particular examples of walks on a cycle, a hypercube and a complete graph, quantum walks provide no speed-up in mixing over the classical counterparts. In addition, non-unitary quantum walks (i.e., walks with decoherence) are considered and a criterion for their convergence to the unique stationary distribution is derived.

  17. Leaf-to-leaf distances in Catalan tree graphs

    E-Print Network [OSTI]

    Andrew M. Goldsborough; Jonathan M. Fellows; Matthew Bates; S. Alex Rautu; George Rowlands; Rudolf A. Römer

    2015-03-02T23:59:59.000Z

    We study the average leaf-to-leaf path lengths on ordered Catalan tree graphs with $n$ nodes and show that these are equivalent to the average length of paths starting from the root node. We give an explicit analytic formula for the average leaf-to-leaf path length as a function of separation of the leaves and study its asymptotic properties. At the heart of our method is a strategy based on an abstract graph representation of generating functions which we hope can be useful also in other contexts.

  18. Vacuum Energy and Repulsive Casimir Forces in Quantum Star Graphs

    E-Print Network [OSTI]

    S. A. Fulling; L. Kaplan; J. H. Wilson

    2007-03-27T23:59:59.000Z

    Casimir pistons are models in which finite Casimir forces can be calculated without any suspect renormalizations. It has been suggested that such forces are always attractive, but we present several counterexamples, notably a simple type of quantum graph in which the sign of the force depends upon the number of edges. We also show that Casimir forces in quantum graphs can be reliably computed by summing over the classical orbits, and study the rate of convergence of the periodic orbit expansion. In generic situations where no analytic expression is available, the sign and approximate magnitude of Casimir forces can often be obtained using only the shortest classical orbits.

  19. Between automation and exploration: SAS graphing techniques for visualization of survey data

    E-Print Network [OSTI]

    Yu, Alex

    Between automation and exploration: SAS graphing techniques for visualization of survey data Chong of survey data. There is always a tension between automation and exploration. Automation is a common to automate the graphing processes via SAS/Macros and SAS/Graph. However, hidden patterns of the data may

  20. Message-passing for Inference and Optimization of Real Variables on Sparse Graphs

    E-Print Network [OSTI]

    Wong, Michael K Y

    Message-passing for Inference and Optimization of Real Variables on Sparse Graphs K. Y. Michael with extensive inter-dependencies among the variables, the graph-based models can be solved by passing messages between neighbouring variables on the graphs. This message-passing approach has gained recent success

  1. Rapid Multipole Graph Drawing on the GPU Apeksha Godiyal*, Jared Hoberock*, Michael Garland

    E-Print Network [OSTI]

    Garland, Michael

    Rapid Multipole Graph Drawing on the GPU Apeksha Godiyal*, Jared Hoberock*, Michael Garland task of drawing large graphs. This paper describes a new parallel anal- ysis of the multipole method of graph drawing to support its efficient GPU implementation. We use a variation of the Fast Multipole

  2. THE MATCHING ENERGY OF A GRAPH IVAN GUTMAN AND STEPHAN WAGNER

    E-Print Network [OSTI]

    Wagner, Stephan

    ) was obtained [4, 13, 20], and recalling the definition of graph energy, Eq. (2), we straightforwardly arrive at. Then, (5) ME(G) = n i=1 |µi|. Eq. (5) could be considered as the definition of matching energyTHE MATCHING ENERGY OF A GRAPH IVAN GUTMAN AND STEPHAN WAGNER Abstract. The energy of a graph G

  3. Effective Graph Classification Based on Topological and Label Attributes , Murat Semerci2

    E-Print Network [OSTI]

    Zaki, Mohammed Javeed

    online 12 June 2012 in Wiley Online Library (wileyonlinelibrary.com). Abstract: Graph classificationEffective Graph Classification Based on Topological and Label Attributes Geng Li1 , Murat Semerci2 propose an alternative approach to graph classification that is based on feature vectors constructed from

  4. The smallest k-regular h-edge-connected graphs without , Douglas B. West

    E-Print Network [OSTI]

    West, Douglas B.

    -regular graph with no cut-edge has a 1-factor. This has many generalizations. Showing that every kThe smallest k-regular h-edge-connected graphs without 1-factors John Ganci , Douglas B. West March-regular (k - 1)-edge-connected graph of even order has a 1-factor is a standard elementary exercise (#3

  5. Loops in Reeb Graphs of 2-Manifolds Kree Cole-McLaughlin

    E-Print Network [OSTI]

    Pascucci, Valerio

    -resolution versions of the Reeb graph have lead to data-base search methods for topologically similar geo- metric and scientific data. Specifically, we study Reeb graphs, which express the connectivity of level sets. These graphs have been used in the past to con- struct data structures and user-interfaces for modeling

  6. Graph Databases for Large-Scale Healthcare Systems: A Framework for Efficient Data Management and Data Services

    SciTech Connect (OSTI)

    Park, Yubin [University of Texas at Austin] [University of Texas at Austin; Shankar, Mallikarjun [ORNL] [ORNL; Park, Byung H [ORNL] [ORNL; Ghosh, Dr. Joydeep [University of Texas at Austin] [University of Texas at Austin

    2014-01-01T23:59:59.000Z

    Designing a database system for both efficient data management and data services has been one of the enduring challenges in the healthcare domain. In many healthcare systems, data services and data management are often viewed as two orthogonal tasks; data services refer to retrieval and analytic queries such as search, joins, statistical data extraction, and simple data mining algorithms, while data management refers to building error-tolerant and non-redundant database systems. The gap between service and management has resulted in rigid database systems and schemas that do not support effective analytics. We compose a rich graph structure from an abstracted healthcare RDBMS to illustrate how we can fill this gap in practice. We show how a healthcare graph can be automatically constructed from a normalized relational database using the proposed 3NF Equivalent Graph (3EG) transformation.We discuss a set of real world graph queries such as finding self-referrals, shared providers, and collaborative filtering, and evaluate their performance over a relational database and its 3EG-transformed graph. Experimental results show that the graph representation serves as multiple de-normalized tables, thus reducing complexity in a database and enhancing data accessibility of users. Based on this finding, we propose an ensemble framework of databases for healthcare applications.

  7. Multi-view kernel construction

    E-Print Network [OSTI]

    Sa, Virginia R.; Gallagher, Patrick W.; Lewis, Joshua M.; Malave, Vicente L.

    2010-01-01T23:59:59.000Z

    5157-z Multi-view kernel construction Virginia R. de Sa ·multiple different graph construction algorithms. The Ng et

  8. Tighter Bounds for Graph Steiner Tree Approximation Gabriel Robins

    E-Print Network [OSTI]

    Zelikovsky, Alexander

    of Computer Science, University of Virginia, Charlottesville, VA 22904 robins@cs.virginia.edu, www.cs.virginia of 1.28 within time O(mn2) (m and n are the numbers of terminals and non-terminals in the graph

  9. Evaluation of Multimodal Graphs for Blind People , STEPHEN BREWSTER

    E-Print Network [OSTI]

    Williamson, John

    sense on people's fingers. Tactile diagrams exist in many forms and they mainly differEvaluation of Multimodal Graphs for Blind People WAI YU 1 , STEPHEN BREWSTER 2 1 Virtual visualisation system and its evaluations. This system is designed to improve blind and visually impaired people

  10. Synchronization Helps Robots to Detect Black Holes in Directed Graphs

    E-Print Network [OSTI]

    Pinotti, Maria Cristina

    nodes are the so called black hole nodes, and once a robot enters in one of them, it is destroyed supported by the Italian CNR Short-Term Mobility Program. #12;1 Introduction The subject of exploring that destroy any entering entity. Such nodes are called black holes, and the exploration of a graph

  11. The TROPOS Analysis Process as Graph Transformation System Paolo Bresciani

    E-Print Network [OSTI]

    Trento-Povo, Italy Abstract Tropos is an agent-oriented methodology that covers soft- ware developmentThe TROPOS Analysis Process as Graph Transformation System Paolo Bresciani ITC-irst via Sommarive of the operational environment of the new software system. In earlier work we have characterized the process of early

  12. Approximating the Diameter of Planar Graphs in Near Linear Time

    E-Print Network [OSTI]

    Yuster, Raphael

    common starting vertex. Let Gin (resp. Gout) be the subgraph of G induced by C and all interior (resp. exterior) vertices to C. Let d(Gin, Gout, G) denote the largest distance in the graph G between a marked vertex in V (Gin) and a marked vertex in V (Gout). In the beginning, all vertices of G are marked and we

  13. Quantitative Analysis of the Full Bitcoin Transaction Graph

    E-Print Network [OSTI]

    Quantitative Analysis of the Full Bitcoin Transaction Graph Dorit Ron and Adi Shamir Department.ron,adi.shamir}@weizmann.ac.il Abstract. The Bitcoin scheme is a rare example of a large scale global payment system in which all and how they spend their bitcoins, the balance of bitcoins they keep in their accounts, and how they move

  14. A spectral graph based approach to analyze hyperspectral data

    E-Print Network [OSTI]

    Bertozzi, Andrea L.

    A spectral graph based approach to analyze hyperspectral data Blake Hunter Department of Mathematics, UCLA 520 Portola Plaza Los Angeles, CA 90095 Email: blakehunter@math.ucla.edu Yifei Lou Department of Mathematics, UCLA 520 Portola Plaza Los Angeles, CA 90095 Email: bertozzi

  15. Brain Mapping Using Topology Graphs Obtained by Surface Segmentation

    E-Print Network [OSTI]

    Linsen, Lars

    Brain Mapping Using Topology Graphs Obtained by Surface Segmentation Fabien Vivodtzev1 , Lars@ucdavis.edu Summary. Brain mapping is a technique used to alleviate the tedious and time- consuming process of annotating brains by mapping existing annotations from brain atlases to individual brains. We introduce

  16. Asymmetric Structure-Preserving Subgraph Queries for Large Graphs

    E-Print Network [OSTI]

    Choi, Byron "Koon Kau"

    Asymmetric Structure-Preserving Subgraph Queries for Large Graphs Zhe Fan1 Byron Choi1 Jianliang Xu the novel cyclic group based encryption so that query processing is transformed into a series of private are effective. I. INTRODUCTION Subgraph queries (via subgraph isomorphism) are a fun- damental and powerful

  17. A Simple Approach to Abductive Inference using Conceptual Graphs

    E-Print Network [OSTI]

    Pagnucco, Maurice

    A Simple Approach to Abductive Inference using Conceptual Graphs Maurice Pagnucco Knowledge Systems, Australia. email: morri@cs.su.oz.au fax : +61­2­692­3838 Abstract Abductive reasoning (or simply abduction) is a form of logical in­ ference that aims to derive plausible explanations for data. The term ``abduction

  18. A Numerical Optimization Approach to General Graph Drawing

    E-Print Network [OSTI]

    Paul Heckbert Bruce Maggs Omar Ghattas, Civil and Environmental Engineering Mark Wegman, IBM T . J Maggs, and Mark Wegman. I am especially grateful that they allowed me to pursue a dissertation. I owe my interest in graph drawing to Mark Wegman, who introduced me to the area when I was an MIT

  19. Unicyclic graphs with large energy Eric Ould Dadah Andriantiana 1

    E-Print Network [OSTI]

    Wagner, Stephan

    of Mathematical Sciences Mathematics Division Stellenbosch University Private Bag X1, Matieland 7602 South Africa work supported by the National Research Foundation of South Africa under grant number 70560. PreprintUnicyclic graphs with large energy Eric Ould Dadah Andriantiana 1 and Stephan Wagner 2 Department

  20. Spectral Decision Diagrams Using Graph Transformations Mitchell Thornton Rolf Drechsler

    E-Print Network [OSTI]

    Thornton, Mitchell

    Spectral Decision Diagrams Using Graph Transformations #3; Mitchell Thornton Rolf Drechsler Department of Electrical and Computer Engineering Siemens AG Mississippi State University Corporate Technology Mississippi State, MS 39762 81730 Munich, Germany mitch@ece.msstate.edu rolf.drechsler@mchp.siemens

  1. Table of Contents Part 1: Climate Graphs Activity

    E-Print Network [OSTI]

    . Quantity. How much precipitation falls? What is the general trend east to west in Texas concerningTable of Contents Part 1: Climate Graphs Activity Part 2: Texas Climate Handout Maps for transparencies: a. Texas Average Annual Temperature b. Texas Average Annual Precipitation c. Texas Climate

  2. An Approach to Security Policy Configuration Using Semantic Threat Graphs

    E-Print Network [OSTI]

    Foley, Simon

    An Approach to Security Policy Configuration Using Semantic Threat Graphs Simon N. Foley, in turn, unnecessarily expose the enterprise to known threats. This paper pro- poses a threat management- nomic configuration of security mechanisms. This knowledge is mod- eled in terms of Semantic Threat

  3. Insider Threat Detection using Stream Mining and Graph Mining

    E-Print Network [OSTI]

    Hamlen, Kevin W.

    Insider Threat Detection using Stream Mining and Graph Mining Pallabi Parveen, Jonathan Evans threats who attempt to conceal their activities by varying their behaviors over time. This paper applies of insider threat detection, demonstrating that the ensemble-based approach is significantly more effective

  4. Decentralized Semantic Threat Graphs Simon N. Foley1

    E-Print Network [OSTI]

    Foley, Simon

    Decentralized Semantic Threat Graphs Simon N. Foley1 William M. Fitzgerald1 Cork Constraint.foley@cs.ucc.ie wfitzgerald@4c.ucc.ie Abstract. Threat knowledge-bases such as those maintained by MITRE and NIST provide a basis with which to mitigate known threats to an enterprise. These centralised knowledge-bases assume

  5. Weighted Graph Cuts without Eigenvectors: A Multilevel Approach

    E-Print Network [OSTI]

    to handle data that is not linearly separable; spectral clustering and kernel k-means are two of the main different methods--in particular, a general weighted kernel k-means objective is mathematically equivalent multilevel algorithm removes this restriction by using kernel k-means to optimize weighted graph cuts

  6. Graph Based K-Means Clustering Laurent Galluccioa,c

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Graph Based K-Means Clustering Laurent Galluccioa,c , Olivier Michelb , Pierre Comona , Alfred O the generalized Lloyd algorithm, also known as k-means, which circumvents its well known initialization problems for estimating of the number of clusters present and determining good centroid locations to initialize the k-means

  7. Mining Large Graphs And Streams Using Matrix And Tensor Tools

    E-Print Network [OSTI]

    Kolda, Tamara G.

    RESULTS The graphs at right show overall variability distribution estimated for the Pentium D 800 where a core no longer works properly. In the Sun T1 Niagara cores this is done with a built-in- self processors we record the temperature at which the failure occurred and adjust to the frequencies

  8. Math 304 Handout: Linear algebra, graphs, and networks.

    E-Print Network [OSTI]

    Anshelevich, Michael

    . · The World Wide Web is a directed graph, with web pages as vertices and links as edges. · Towns connected on the web, all the words that they contain. Again, an efficient way to do this is using a (very, very large) matrix. Each column corresponds to a web page, each row to a word, and each entry is 1 if a particular

  9. A SPATIAL WEB GRAPH MODEL WITH LOCAL INFLUENCE REGIONS

    E-Print Network [OSTI]

    Pralat, Pawel

    mining technique, web pages are often represented as vectors in a word-document space. Using LatentA SPATIAL WEB GRAPH MODEL WITH LOCAL INFLUENCE REGIONS W. AIELLO, A. BONATO, C. COOPER, J. JANSSEN-degree distribution, with exponent in [2, ) depending on the parameters, and with concentration for a wide range of in

  10. Towards Efficient Query Processing on Massive Time-Evolving Graphs

    E-Print Network [OSTI]

    Miller, John A.

    Email: {ar, ara, laks, jam}@cs.uga.edu Abstract--Time evolving graph (TEG) is increasingly being used on massive TEGs is central to building powerful analytic applications for these domains. Unfortunately effective for processing massive TEGs. Towards designing scalable mechanisms for answering TEG queries

  11. Distanceregular graphs having an eigenvalue of small multiplicity

    E-Print Network [OSTI]

    Martin, Bill

    , results of Godsil [12] and Terwilliger [19], to allow computer generation of all feasible intesection of Godsil and Terwilliger and on results in this paper, we now have the diameter bound d Ÿ 3m \\Gamma 8 for m of graph representa­ tions is outlined, theorems of Godsil and Terwilliger are stated and several

  12. On the edgeconnectivity of Cartesian product graphs # Sandi Klavzar

    E-Print Network [OSTI]

    Klavzar, Sandi

    edge cut of G#H, then either S is induced by a minimum edge cut of a factor, or S is a set of edges is given and the structure of minimum edge cuts is described. It is also proved that the connectivity product of graphs; edge­connectivity; minimum edge cuts; AMS subject classification (2000): 05C40 1

  13. Spectra of graphs and semi-conducting polymers

    E-Print Network [OSTI]

    Philipp Schapotschnikow; Sven Gnutzmann

    2008-02-04T23:59:59.000Z

    We study the band gap in some semi-conducting polymers with two models: H\\"uckel molecular orbital theory and the so-called free electron model. The two models are directly related to spectral theory on combinatorial and metric graphs.

  14. Secret sharing schemes on graphs L aszl o Csirmaz

    E-Print Network [OSTI]

    Csirmaz, László

    Secret sharing schemes on graphs L#19;aszl#19;o Csirmaz Mathematical Institute of the Hungarian secret sharing scheme based on G is a method to distribute a secret data among the vertices of G, the participants, so that a subset of participants can recover the secret if they contain an edge of G, otherwise

  15. On Linear Secret Sharing for Connectivity in Directed Graphs

    E-Print Network [OSTI]

    Beimel, Amos

    On Linear Secret Sharing for Connectivity in Directed Graphs Amos Beimel 1 and Anat Paskin 2 1 Dept, Israel. Abstract. In this work we study linear secret sharing schemes for s­t connectivity in directed.e., edges) can reconstruct the secret if it contains a path from node s to node t. We prove that in every

  16. On Linear Secret Sharing for Connectivity in Directed Graphs

    E-Print Network [OSTI]

    Beimel, Amos

    On Linear Secret Sharing for Connectivity in Directed Graphs Amos Beimel1 and Anat Paskin2 1 Dept, Israel. Abstract. In this work we study linear secret sharing schemes for s-t connectivity in directed.e., edges) can reconstruct the secret if it contains a path from node s to node t. We prove that in every

  17. (Co)Algebraic Characterizations of Signal Flow Graphs

    E-Print Network [OSTI]

    Rutten, Jan

    Signal flow graphs are a graphical representation for the analysis, modeling and evaluation of linear as a linear combination of the input and the registers. That is, the dynamics of a circuit can be expressed as a system of linear of equations, one for each register. Since we consider open circuits, the corresponding

  18. THE GROUP OF SYMMETRIES OF THE TOWER OF HANOI GRAPH

    E-Print Network [OSTI]

    Behrstock, Jason

    THE GROUP OF SYMMETRIES OF THE TOWER OF HANOI GRAPH SO EUN PARK The classical Tower of Hanoi puzzle the tower of disks to another peg, moving one topmost disk at a time while never stacking a disk referred to as the Tower of Hanoi problem. Figure 1. Convention for labeling k pegs and n disks

  19. A graph-based network-vulnerability analysis system

    SciTech Connect (OSTI)

    Swiler, L.P.; Phillips, C.; Gaylor, T.

    1998-05-03T23:59:59.000Z

    This paper presents a graph based approach to network vulnerability analysis. The method is flexible, allowing analysis of attacks from both outside and inside the network. It can analyze risks to a specific network asset, or examine the universe of possible consequences following a successful attack. The analysis system requires as input a database of common attacks, broken into atomic steps, specific network configuration and topology information, and an attacker profile. The attack information is matched with the network configuration information and an attacker profile to create a superset attack graph. Nodes identify a stage of attack, for example the class of machines the attacker has accessed and the user privilege level he or she has compromised. The arcs in the attack graph represent attacks or stages of attacks. By assigning probabilities of success on the arcs or costs representing level of effort for the attacker, various graph algorithms such as shortest path algorithms can identify the attack paths with the highest probability of success.

  20. A graph-based network-vulnerability analysis system

    SciTech Connect (OSTI)

    Swiler, L.P.; Phillips, C. [Sandia National Labs., Albuquerque, NM (United States); Gaylor, T. [3M, Austin, TX (United States). Visual Systems Div.

    1998-01-01T23:59:59.000Z

    This report presents a graph-based approach to network vulnerability analysis. The method is flexible, allowing analysis of attacks from both outside and inside the network. It can analyze risks to a specific network asset, or examine the universe of possible consequences following a successful attack. The analysis system requires as input a database of common attacks, broken into atomic steps, specific network configuration and topology information, and an attacker profile. The attack information is matched with the network configuration information and an attacker profile to create a superset attack graph. Nodes identify a stage of attack, for example the class of machines the attacker has accessed and the user privilege level he or she has compromised. The arcs in the attack graph represent attacks or stages of attacks. By assigning probabilities of success on the arcs or costs representing level-of-effort for the attacker, various graph algorithms such as shortest-path algorithms can identify the attack paths with the highest probability of success.

  1. Using Battery Level as Metric for Graph Planarization Jovan Radak, Nathalie Mitton, and David Simplot-Ryl

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    only a subset of its neighborhood by keeping connectivity. Then, a node adjusts its range for scalability and energy efficiency. It is often based on graph reduction performed through the use of Gabriel Graph or Relative Neighborhood Graph. This graph reduction is usually based on geometric values

  2. Constructing and sampling graphs with a given joint degree distribution.

    SciTech Connect (OSTI)

    Pinar, Ali; Stanton, Isabelle (UC Berkeley)

    2010-09-01T23:59:59.000Z

    One of the most influential recent results in network analysis is that many natural networks exhibit a power-law or log-normal degree distribution. This has inspired numerous generative models that match this property. However, more recent work has shown that while these generative models do have the right degree distribution, they are not good models for real life networks due to their differences on other important metrics like conductance. We believe this is, in part, because many of these real-world networks have very different joint degree distributions, i.e. the probability that a randomly selected edge will be between nodes of degree k and l. Assortativity is a sufficient statistic of the joint degree distribution, and it has been previously noted that social networks tend to be assortative, while biological and technological networks tend to be disassortative. We suggest understanding the relationship between network structure and the joint degree distribution of graphs is an interesting avenue of further research. An important tool for such studies are algorithms that can generate random instances of graphs with the same joint degree distribution. This is the main topic of this paper and we study the problem from both a theoretical and practical perspective. We provide an algorithm for constructing simple graphs from a given joint degree distribution, and a Monte Carlo Markov Chain method for sampling them. We also show that the state space of simple graphs with a fixed degree distribution is connected via end point switches. We empirically evaluate the mixing time of this Markov Chain by using experiments based on the autocorrelation of each edge. These experiments show that our Markov Chain mixes quickly on real graphs, allowing for utilization of our techniques in practice.

  3. LDRD final report : first application of geospatial semantic graphs to SAR image data.

    SciTech Connect (OSTI)

    Brost, Randolph C.; McLendon, William Clarence,

    2013-01-01T23:59:59.000Z

    Modeling geospatial information with semantic graphs enables search for sites of interest based on relationships between features, without requiring strong a priori models of feature shape or other intrinsic properties. Geospatial semantic graphs can be constructed from raw sensor data with suitable preprocessing to obtain a discretized representation. This report describes initial work toward extending geospatial semantic graphs to include temporal information, and initial results applying semantic graph techniques to SAR image data. We describe an efficient graph structure that includes geospatial and temporal information, which is designed to support simultaneous spatial and temporal search queries. We also report a preliminary implementation of feature recognition, semantic graph modeling, and graph search based on input SAR data. The report concludes with lessons learned and suggestions for future improvements.

  4. A Simple Method for Finding the Scattering Coefficients of Quantum Graphs

    E-Print Network [OSTI]

    Seth S. Cottrell

    2015-03-01T23:59:59.000Z

    Quantum walks are roughly analogous to classical random walks, and like classical walks they have been used to find new (quantum) algorithms. When studying the behavior of large graphs or combinations of graphs it is useful to find the response of a subgraph to signals of different frequencies. In so doing we can replace an entire subgraph with a single vertex with frequency dependent scattering coefficients. In this paper a simple technique for quickly finding the scattering coefficients of any quantum graph will be presented. These scattering coefficients can be expressed entirely in terms of the characteristic polynomial of the graph's time step operator. Moreover, with these in hand we can easily derive the "impulse response" which is the key to predicting the response of a graph to any signal. This gives us a powerful set of tools for rapidly understanding the behavior of graphs or for reducing a large graph into its constituent subgraphs regardless of how they are connected.

  5. A Mathematical Analysis of the R-MAT Random Graph Generator

    SciTech Connect (OSTI)

    Groer, Christopher S [ORNL; Sullivan, Blair D [ORNL; Poole, Stephen W [ORNL

    2011-01-01T23:59:59.000Z

    The R-MAT graph generator introduced by Chakrabarti, Faloutsos, and Zhan offers a simple, fast method for generating very large directed graphs. These properties have made it a popular choice as a method of generating graphs for objects of study in a variety of disciplines, from social network analysis to high performance computing. We analyze the graphs generated by R-MAT and model the generator in terms of occupancy problems in order to prove results about the degree distributions of these graphs. We prove that the limiting degree distributions can be expressed as a mixture of normal distributions, contradicting the widely held belief that R-MAT degree distributions exhibit the power law or scale free distribution observed in many real world graphs. Additionally, this paper offers an efficient computational technique for computing the exact degree distribution, as well as concise expressions for a number of properties of R-MAT graphs.

  6. M&Ms4Graphs: Multi-scale, Multi-dimensional Graph Analytics Tools for Cyber-Security

    E-Print Network [OSTI]

    . "Statistical and Hierarchical Graph Analysis for Cyber Security." SIAM Conference on Discrete Mathematics effort is made possible by the Pacific Northwest National Laboratory through funding provided by the U.S. Department of Energy. For more information on the science you see here, please contact: Sutanay Choudhury

  7. A Graph Analytic Metric for Mitigating Advanced Persistent Threat

    SciTech Connect (OSTI)

    Johnson, John R.; Hogan, Emilie A.

    2013-06-04T23:59:59.000Z

    This paper introduces a novel graph analytic metric that can be used to measure the potential vulnerability of a cyber network to specific types of attacks that use lateral movement and privilege escalation such as the well known Pass The Hash, (PTH). The metric is computed from an oriented subgraph of the underlying cyber network induced by selecting only those edges for which a given property holds between the two vertices of the edge. The metric with respect to a select node on the subgraph is defined as the likelihood that the select node is reachable from another arbitrary node in the graph. This metric can be calculated dynamically from the authorization and auditing layers during the network security authorization phase and will potentially enable predictive deterrence against attacks such as PTH.

  8. A characterization of Q-polynomial distance-regular graphs

    E-Print Network [OSTI]

    Jurisic, Aleksandar; Zitnik, Arjana

    2009-01-01T23:59:59.000Z

    We obtain the following characterization of $Q$-polynomial distance-regular graphs. Let $\\G$ denote a distance-regular graph with diameter $d\\ge 3$. Let $E$ denote a minimal idempotent of $\\G$ which is not the trivial idempotent $E_0$. Let $\\{\\theta_i^*\\}_{i=0}^d$ denote the dual eigenvalue sequence for $E$. We show that $E$ is $Q$-polynomial if and only if (i) the entry-wise product $E \\circ E$ is a linear combination of $E_0$, $E$, and at most one other minimal idempotent of $\\G$; (ii) there exists a complex scalar $\\beta$ such that $\\theta^*_{i-1}-\\beta \\theta^*_i + \\theta^*_{i+1}$ is independent of $i$ for $1 \\le i \\le d-1$; (iii) $\\theta^*_i \

  9. Qubits from Adinkra Graph Theory via Colored Toric Geometry

    E-Print Network [OSTI]

    Aadel, Y; Benslimane, Z; Sedra, M B; Segui, A

    2015-01-01T23:59:59.000Z

    We develop a new approach to deal with qubit information systems using toric geometry and its relation to Adinkra graph theory. More precisely, we link three different subjects namely toric geometry, Adinkras and quantum information theory. This one to one correspondence may be explored to attack qubit system problems using geometry considered as a powerful tool to understand modern physics including string theory. Concretely, we examine in some details the cases of one, two, and three qubits, and we find that they are associated with \\bf CP^1, \\bf CP^1\\times CP^1 and \\bf CP^1\\times CP^1\\times CP^1 toric varieties respectively. Using a geometric procedure referred to as colored toric geometry, we show that the qubit physics can be converted into a scenario handling toric data of such manifolds by help of Adinkra graph theory. Operations on toric information can produce universal quantum gates.

  10. Spectral properties of microwave graphs with local absorption

    E-Print Network [OSTI]

    M. Allgaier; S. Gehler; S. Barkhofen; H. -J. Stöckmann; U. Kuhl

    2014-03-30T23:59:59.000Z

    The influence of absorption on the spectra of microwave graphs has been studied experimentally. The microwave networks were made up of coaxial cables and T junctions. First, absorption was introduced by attaching a 50 Ohm load to an additional vertex for graphs with and without time-reversal symmetry. The resulting level-spacing distributions were compared with a generalization of the Wigner surmise in the presence of open channels proposed recently by Poli et al. [Phys. Rev. Lett. 108, 174101 (2012)]. Good agreement was found using an effective coupling parameter. Second, absorption was introduced along one individual bond via a variable microwave attenuator, and the influence of absorption on the length spectrum was studied. The peak heights in the length spectra corresponding to orbits avoiding the absorber were found to be independent of the attenuation, whereas, the heights of the peaks belonging to orbits passing the absorber once or twice showed the expected decrease with increasing attenuation.

  11. Deciding Graph MSO Properties: Has it all been told already?

    E-Print Network [OSTI]

    Gajarský, Jakub

    2012-01-01T23:59:59.000Z

    A famous result of Courcelle claims that on graphs of bounded tree-width extensions for the MSO1 case are presented also in [Ganian, IPEC2011]. We take a general approach, proving that the MSO model-checking problem admits an FPT algorithm with an elementary dependence on the formula on all classes of trees of bounded height. This result, via standard logic interpretation, implies that all MSO2 properties \\phi are decidable in FPT with an elemen...

  12. Connection probability for random graphs with given degree sequence

    E-Print Network [OSTI]

    Xinping Xu

    2007-08-20T23:59:59.000Z

    Recently, the classical configuration model for random graphs with given degree distribution has been extensively used as a null model in contraposition to real networks with the same degree distribution. In this paper, we briefly review the applications of this model and derive analytical expression for connection probability by the expanding coefficient method. We also use our expanding coefficient method to obtain the connection probability for the directed configuration model.

  13. A Spatiotemporal Graph Model for Rainfall Event Identification and Representation

    E-Print Network [OSTI]

    Liu, Weibo

    2014-04-21T23:59:59.000Z

    of a storm ? The spread of a wildfire ? Other dynamic geographic phenomena from time series of snapshot datasets 3Research Objectives Identify the whole lifecycle of rainstorms from time series of snapshot datasets; Represent and analyze the rainstorms... based on a spatiotemporal graph model; Analyze the spatiotemporal characteristics of rainstorms. Data ? NEXRAD (Next generation Radar) ? Hourly precipitation estimate ? Cover more than 2/3 of the nation Rainstorms’ Lifecycle Identification Delineate...

  14. Strong Integer Additive Set-valued Graphs: A Creative Review

    E-Print Network [OSTI]

    N. K. Sudev; K. A. Germina; K. P. Chithra

    2015-04-23T23:59:59.000Z

    For a non-empty ground set $X$, finite or infinite, the {\\em set-valuation} or {\\em set-labeling} of a given graph $G$ is an injective function $f:V(G) \\to \\mathcal{P}(X)$, where $\\mathcal{P}(X)$ is the power set of the set $X$. A set-indexer of a graph $G$ is an injective set-valued function $f:V(G) \\to \\mathcal{P}(X)$ such that the function $f^{\\ast}:E(G)\\to \\mathcal{P}(X)-\\{\\emptyset\\}$ defined by $f^{\\ast}(uv) = f(u){\\ast} f(v)$ for every $uv{\\in} E(G)$ is also injective., where $\\ast$ is a binary operation on sets. An integer additive set-indexer is defined as an injective function $f:V(G)\\to \\mathcal{P}({\\mathbb{N}_0})$ such that the induced function $g_f:E(G) \\to \\mathcal{P}(\\mathbb{N}_0)$ defined by $g_f (uv) = f(u)+ f(v)$ is also injective, where $\\mathbb{N}_0$ is the set of all non-negative integers and $\\mathcal{P}(\\mathbb{N}_0)$ is its power set. An IASI $f$ is said to be a strong IASI if $|f^+(uv)|=|f(u)|\\,|f(v)|$ for every pair of adjacent vertices $u,v$ in $G$. In this paper, we critically and creatively review the concepts and properties of strong integer additive set-valued graphs.

  15. A sharp lower bound for the Wiener index of a graph

    E-Print Network [OSTI]

    Balakrishnan, R; Iyer, K V

    2010-01-01T23:59:59.000Z

    Given a simple connected undirected graph G, the Wiener index W(G) of G is defined as half the sum of the distances over all pairs of vertices of G. In practice, G corresponds to what is known as the molecular graph of an organic compound. We obtain a sharp lower bound for W(G) of an arbitrary graph in terms of the order, size and diameter of G.

  16. LIGHT SUBGRAPHS IN PLANAR GRAPHS OF MINIMUM DEGREE 4 AND EDGE-DEGREE 9

    E-Print Network [OSTI]

    Mohar, Bojan

    LIGHT SUBGRAPHS IN PLANAR GRAPHS OF MINIMUM DEGREE 4 AND EDGE-DEGREE 9 B. MOHAR , R. SKREKOVSKI vertices of degree 4 are adjacent. A graph H is light in G if there is a constant w such that every graph is w. Then we also write w(H) w. It is proved that the cycle Cs is light if and only if 3 s 6, where

  17. Materials for Math 13900 Bring to class each day: graph paper ...

    E-Print Network [OSTI]

    Roames, Renee S

    2015-01-08T23:59:59.000Z

    Materials for Math 13900. Bring to class each day: graph paper isometric dot paper unlined paper cm ruler. We will also be using: compass small scissors.

  18. Graphs whose normalized Laplacian matrices are separable as density matrices in quantum mechanics

    E-Print Network [OSTI]

    Chai Wah Wu

    2014-07-23T23:59:59.000Z

    Recently normalized Laplacian matrices of graphs are studied as density matrices in quantum mechanics. Separability and entanglement of density matrices are important properties as they determine the nonclassical behavior in quantum systems. In this note we look at the graphs whose normalized Laplacian matrices are separable or entangled. In particular, we show that the number of such graphs is related to the number of 0-1 matrices that are line sum symmetric and to the number of graphs with at least one vertex of degree 1.

  19. Semi-classical measures on Quantum graphs and the Gau map of the determinant manifold

    E-Print Network [OSTI]

    Boyer, Edmond

    believed that QE does not hold in general for a FIXED quantum graph. In [BKW04], it is proved that QE does

  20. Transitive closure and metric inequality of weighted graphs: detecting protein interaction modules using cliques

    E-Print Network [OSTI]

    Ding, Chris; He, Xiaofeng; Xiong, Hui; Peng, Hanchuan; Holbrook, Stephen R.

    2006-01-01T23:59:59.000Z

    Closure and Metric Inequality of Weighted Graphs – Detectingleads to a transitivity inequality which is equivalentto ultra-metric inequality. This can be used to de?ne

  1. Integrative Protein Function Transfer using Factor Graphs and Heterogeneous Data Sources

    E-Print Network [OSTI]

    Mishra, Bud

    Integrative Protein Function Transfer using Factor Graphs and Heterogeneous Data Sources Antonina, translation initiation, enzymatic catalysis, and immune re- sponse. However, for a large portion of proteins

  2. Global Binary Optimization on Graphs for Classification of High-Dimensional Data

    E-Print Network [OSTI]

    Merkurjev, E; Bae, E; Bertozzi, AL; Tai, XC

    2015-01-01T23:59:59.000Z

    J.H. : Convergence and energy landscape for Cheeger cutmax-flow algorithms for energy minimization in vision. IEEER. : Fast approxi- mate energy minimization via graph cuts.

  3. Conclusions and future work We have pointed out the importance of proximity graphs as scaffolds for clustering

    E-Print Network [OSTI]

    Carreira-Perpiñán, Miguel Á.

    have introduced two new types of proximity graphs based on ensembles of minimum spanning trees, which for non-Euclidean data; study stochastic graphs. 7 Results: dimens. reduction (Isomap) Ellipse, high noise

  4. Abstract--A wide variety of DSP design tools have been developed that incorporate dataflow graph representations into

    E-Print Network [OSTI]

    Bhattacharyya, Shuvra S.

    framework for construction and manipulation of dataflow graphs for DSP system design. To facilitate design of complex systems, our framework includes a powerful integration of C-based procedural programming topologies increases, textual manipulation of graph specifications becomes increasingly important

  5. Groups generated by bounded automata and their schreier graphs 

    E-Print Network [OSTI]

    Bondarenko, Ievgen

    2009-05-15T23:59:59.000Z

    by Bounded Automata and Their Schreier Graphs. (December 2007) Ievgen Bondarenko, B.S., National Taras Shevchenko University of Kyiv, Ukraine; M.S., National Taras Shevchenko University of Kyiv, Ukraine Chair of Advisory Committee: Dr. Rostislav Grigorchuk... maps In Chapter III we study spectral properties and iterations of piecewise linear maps of the form fK(v) = min A?K Av, v?RN, (1.1) where K is a finite set of nonnegative square matrices of fixed dimension and by ?min? we mean component-wise minimum...

  6. Groups generated by bounded automata and their schreier graphs 

    E-Print Network [OSTI]

    Bondarenko, Ievgen

    2008-10-10T23:59:59.000Z

    by Bounded Automata and Their Schreier Graphs. (December 2007) Ievgen Bondarenko, B.S., National Taras Shevchenko University of Kyiv, Ukraine; M.S., National Taras Shevchenko University of Kyiv, Ukraine Chair of Advisory Committee: Dr. Rostislav Grigorchuk... maps In Chapter III we study spectral properties and iterations of piecewise linear maps of the form fK(v) = min A?K Av, v?RN, (1.1) where K is a finite set of nonnegative square matrices of fixed dimension and by “min” we mean component-wise minimum...

  7. AGE: a distributed environment for creating interactive animations of graphs

    E-Print Network [OSTI]

    Veatch, Timothy Richard

    1990-01-01T23:59:59.000Z

    Facility . 5. Aesthetics B. Enhancements . C. Summary REFERENCES 72 73 75 76 80 81 APPENDIX A: ACCESS TO AGE 86 APPENDIX B: SOURCE CODE SUMMARY 93 APPENDIX C: CLIENT PRIMITIVES 98 1. AGESOCKET CONNECT . 2. AGEJvlESSAGE READ. . . 3... to the object with the mouse and selecting one of the operations from the menu that pops-up. This method proves simple enough for beginners and is quick enough for experts. In order to be useful in many situations, a set of primitive graph operations has been...

  8. Compositionality in Synchronous Data Flow: Modular Code Generation from Hierarchical SDF Graphs

    E-Print Network [OSTI]

    Compositionality in Synchronous Data Flow: Modular Code Generation from Hierarchical SDF Graphs in Synchronous Data Flow: Modular Code Generation from Hierarchical SDF Graphs Stavros Tripakis, Dai Bui, Bert of California, Berkeley stavros, daib, eal@eecs.berkeley.edu October 20, 2009 Abstract Hierarchical SDF models

  9. JACOBIANS OF NEARLY COMPLETE AND THRESHOLD GRAPHS SERGUEI NORINE AND PETER WHALEN

    E-Print Network [OSTI]

    Norin, Sergey

    to it as the sandpile group [7]. Seven years later, Bacher et al referred to it alternatively as the Picard group. The Jacobian of a graph, also known as the Picard Group, Sandpile Group, or Critical Group, is a discrete is odd, where k is such that the order of the group is the number of spanning trees of the graph

  10. The power graph of a finite group, II Peter J. Cameron

    E-Print Network [OSTI]

    Cameron, Peter

    The power graph of a finite group, II Peter J. Cameron School of Mathematical Sciences Queen Mary, University of London Mile End Road London E1 4NS, U.K. Abstract The directed power graph of a group G is the digraph with vertex set G, having an arc from y to x whenever x is a power of y; the undirected power

  11. An Updated Taxonomy of Evolutionary Computation Problems using Graph-based

    E-Print Network [OSTI]

    Ashlock, Dan

    An Updated Taxonomy of Evolutionary Computation Problems using Graph-based Evolutionary Algorithms some other groups of problems scatter across the taxonomy. This paper updates an earlier taxonomy of 23, for the self-avoiding-walk problems corrects, a taxonomy of 23 problems given in [8]. The list of graphs

  12. Contraction decomposition in h-minor-free graphs and algorithmic applications

    E-Print Network [OSTI]

    Demaine, Erik D.

    We prove that any graph excluding a fixed minor can have its edges partitioned into a desired number k of color classes such that contracting the edges in any one color class results in a graph of treewidth linear in k. ...

  13. Fault-Tolerant Exploration of an Unknown Dangerous Graph by Scattered Agents

    E-Print Network [OSTI]

    Flocchini, Paola

    Fault-Tolerant Exploration of an Unknown Dangerous Graph by Scattered Agents Paola Flocchini1 a network where there are dangerous sites (black holes) that eliminate any incoming searcher without leaving a discernible trace. Dangerous graph exploration (Dge) extends the Bhs problem to include dangerous links (black

  14. Management of Security Policy Configuration using a Semantic Threat Graph Approach

    E-Print Network [OSTI]

    Foley, Simon

    Management of Security Policy Configuration using a Semantic Threat Graph Approach Simon N. Foley, in turn, unnec- essarily expose the enterprise to known threats. This paper proposes a threat management Threat Graphs, a variation of the tradi- tional Threat/Attack Tree, extended in order to relate semantic

  15. KOHONEN NETWORKS WITH GRAPH-BASED AUGMENTED METRICS Peter Andras and Olusola Idowu

    E-Print Network [OSTI]

    Andras, Peter

    include: bisecting k-means clustering [2], principal component analysis [3], independent component that is based on the comparison of word consecutiveness graphs of documents. We show that using the proposed distance metric comparison of word frequency vectors. Our results indicate that word consecutiveness graph

  16. A near-optimal approximation algorithm for Asymmetric TSP1 on embedded graphs2

    E-Print Network [OSTI]

    Erickson, Jeff

    algorithm of Oveis Gharan and Saberi [SODA 2011], which applies only to graphs15 with orientable genus g and Saberi [11] described a polynomial-time9 O( g log g)-approximation algorithm when the input includes and Saberi [11] applies only to23 graphs embedded on orientable surfaces.24 Chekuri and Sidiropoulos [3

  17. Feature Tracking Using Reeb Graphs Gunther H. Weber1,2, Peer-Timo Bremer3,

    E-Print Network [OSTI]

    in Combustion Simulations · Application: ­ Simulation of premixed lean hydrogen flames under different levels TVCG, Analyzing and tracking burning structures in lean premixed hydrogen flames] #12;Feature Tracking Using Reeb Graphs 11 Tracking Graph Extraction Pipeline 1. Concatenate to obtain 4D mesh 2. Extract

  18. THE RADIO NUMBERS OF ALL GRAPHS OF ORDER n AND DIAMETER n -2

    E-Print Network [OSTI]

    Tomova, Maggy

    THE RADIO NUMBERS OF ALL GRAPHS OF ORDER n AND DIAMETER n - 2 KATHERINE BENSON, MATTHEW PORTER, AND MAGGY TOMOVA Abstract. A radio labeling of a connected graph G is a function c : V (G) Z+ such that for every two distinct vertices u and v of G distance(u, v) + |c(u) - c(v)| 1 + diameter(G). The radio

  19. Actes JFPC 2008 LS(Graph): Un cadre de recherche locale pour des

    E-Print Network [OSTI]

    Deville, Yves

    le diam`etre d'un arbre) parce que ceux-ci sont d´ej`a impl´ement´es dans LS(Graph). Le program- meur recherche heu- ristiques et metaheuristiques. LS(Graph) est con¸cu et impl´ement´e en COMET (le code source

  20. Scheduling tree-shaped task graphs to minimize memory and makespan

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Scheduling tree-shaped task graphs to minimize memory and makespan Loris Marchal CNRS experimental evaluation using realistic trees. Keywords-scheduling; makespan-memory tradeoff; tree- shaped task.vivien@inria.fr Abstract--This paper investigates the execution of tree- shaped task graphs using multiple processors. Each

  1. NEW DATA MODEL FOR GRAPH-CUT SEGMENTATION: APPLICATION TO AUTOMATIC MELANOMA DELINEATION

    E-Print Network [OSTI]

    Lezoray, Olivier

    NEW DATA MODEL FOR GRAPH-CUT SEGMENTATION: APPLICATION TO AUTOMATIC MELANOMA DELINEATION R. K but also texture and shape information. For melanoma images, we also introduce skin chromophore features- tion to melanoma delineation compares favorably to manual delineation and related graph

  2. Fast solution of NP-hard coloring problems on large random graphs

    E-Print Network [OSTI]

    Bedini, Andrea

    2010-01-01T23:59:59.000Z

    Combining tree decomposition and transfer matrix techniques provides a highly efficient and very general algorithm for computing exact partition functions of statistical models defined on large graphs. We illustrate this by considering the hard problem of computing the exact number of vertex colorings for randomly generated planar graphs with up to N = 100 vertices.

  3. Timed Event Graphs with variable resources: asymptotic behavior, representation in (min,+)

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    -1032" #12;1. Introduction Timed Event Graphs (TEG's), which constitute a subclass of timed Petri nets precisely, we define a class of timed Petri nets, called TEG's with variable resources, which can be likened to linear time-varying systems over ´Ñ Ò ·µ algebra - a particular dioid. These graphs (TEG's on which

  4. Disturbance Decoupling of Timed Event Graphs by output feedback controller Mehdi Lhommeau, Laurent Hardouin, Bertrand Cottenceau

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    .hardouin, bertrand.cottenceau]@istia.univ-angers.fr Abstract This paper deals with control of Timed Event Graphs (TEG). In a first part the disturbance decoupling problem for TEG is defined. In a second part we propose is introduced for a particular class of Discrete Event Dynamic Systems (DEDS) called Timed Event Graphs (TEG

  5. DATABASE Open Access RAG: An update to the RNA-As-Graphs resource

    E-Print Network [OSTI]

    Schlick, Tamar

    DATABASE Open Access RAG: An update to the RNA-As-Graphs resource Joseph A Izzo1 , Namhee Kim1 utilize the benefits of relational database, and improvements to several of the utilities such as directed/labeled graphs and a subgraph search program. Conclusions: The RAG updates presented here augment the database

  6. Enterprise Social Network Analysis and Modeling: A Tale of Two Graphs

    E-Print Network [OSTI]

    Li, Li Erran

    Enterprise Social Network Analysis and Modeling: A Tale of Two Graphs Jin Cao1, Hongyu Gao2, Li to understand how people are using these social networks. Unlike the public social networks like Facebook social networks are also governed by an organization graph. Based on a six month dataset collected from

  7. MadGraph/MadEvent 4 SUSY, new models, matching and more!

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Alwall - MadGraph/MadEvent 4 513 Mar 2007 What is new in MG/ME 4? Web-oriented, modular software banner #12;Johan Alwall - MadGraph/MadEvent 4 713 Mar 2007 Whole chain on web or downloaded and run locally Cards filled on the web or uploaded (reusable) Modular structure ­ easy to interface to other

  8. Covering Cuts in Bridgeless Cubic Graphs Sylvia BOYD, Satoru IWATA, Kenjiro TAKAZAWA

    E-Print Network [OSTI]

    are interested in algorithms for finding 2-factors that cover certain prescribed edge-cuts in bridgeless cubic graphs. We present an algorithm for finding a minimum-weight 2-factor covering all the 3-edge cuts for finding a 2-factor covering all the 3- and 4-edge cuts in bridgeless cubic graphs. Both

  9. A conjecture of Biggs concerning the resistance of a distance-regular graph

    E-Print Network [OSTI]

    Markowsky, Greg

    2010-01-01T23:59:59.000Z

    Previously, Biggs has conjectured that the resistance between any two points on a distance-regular graph of valency greater than 2 is bounded by twice the resistance between adjacent points. We prove this conjecture, give the sharp constant for the inequality, and display the graphs for which the conjecture most nearly fails. Some necessary background material is included, as well as some consequences.

  10. Dig-ta Video, Learn-ng Styes, and Student Understanding of Kinematics Graphs

    E-Print Network [OSTI]

    Zollman, Dean

    Dig-ta Video, Learn-ng Styes, and Student Understanding of Kinematics Graphs Teresa Larkin Video, Learning Styles, and Student Understanding of Kinematics Graphs Introduction Student learning interactive digital video as well preferences and student understanding and their ability to interpret motion

  11. Solving planning-graph by compiling it into CSP Minh Binh Do & Subbarao Kambhampati

    E-Print Network [OSTI]

    Kambhampati, Subbarao

    Solving planning-graph by compiling it into CSP Minh Binh Do & Subbarao Kambhampati Department to adapt CSP search techniques into the backward search phase of Graphplan. This paper describes GP-CSP, a system that does planning by automati- cally converting Graphplan's planning graph into a CSP encoding

  12. Massive Scale Cyber Traffic Analysis: A Driver for Graph Database Research

    SciTech Connect (OSTI)

    Joslyn, Cliff A.; Choudhury, S.; Haglin, David J.; Howe, Bill; Nickless, William K.; Olsen, Bryan K.

    2013-06-19T23:59:59.000Z

    We describe the significance and prominence of network traffic analysis (TA) as a graph- and network-theoretical domain for advancing research in graph database systems. TA involves observing and analyzing the connections between clients, servers, hosts, and actors within IP networks, both at particular times and as extended over times. Towards that end, NetFlow (or more generically, IPFLOW) data are available from routers and servers which summarize coherent groups of IP packets flowing through the network. IPFLOW databases are routinely interrogated statistically and visualized for suspicious patterns. But the ability to cast IPFLOW data as a massive graph and query it interactively, in order to e.g.\\ identify connectivity patterns, is less well advanced, due to a number of factors including scaling, and their hybrid nature combining graph connectivity and quantitative attributes. In this paper, we outline requirements and opportunities for graph-structured IPFLOW analytics based on our experience with real IPFLOW databases. Specifically, we describe real use cases from the security domain, cast them as graph patterns, show how to express them in two graph-oriented query languages SPARQL and Datalog, and use these examples to motivate a new class of "hybrid" graph-relational systems.

  13. Privacy-Preserving Query over Encrypted Graph-Structured Data in Cloud Computing

    E-Print Network [OSTI]

    Hou, Y. Thomas

    Privacy-Preserving Query over Encrypted Graph-Structured Data in Cloud Computing Ning Cao, Zhenyu, Chicago, IL 60616 Email: {cong, kren}@ece.iit.edu Abstract-- In the emerging cloud computing paradigm of privacy-preserving query over encrypted graph-structured data in cloud computing (PPGQ), and establish

  14. WILD QUOTIENT SURFACE SINGULARITIES WHOSE DUAL GRAPHS ARE NOT STAR-SHAPED

    E-Print Network [OSTI]

    Schröer, Stefan

    WILD QUOTIENT SURFACE SINGULARITIES WHOSE DUAL GRAPHS ARE NOT STAR-SHAPED HIROYUKI ITO AND STEFAN- zini on wild quotient singularities in dimension two. Using Kato's theory of log structures and log of Heisenberg groups lead to examples of wild quotient singularities where the dual graph contains at least two

  15. Graph Mining for Object Tracking in Videos Fabien Diot1,2

    E-Print Network [OSTI]

    Graph Mining for Object Tracking in Videos Fabien Diot1,2 , Elisa Fromont1 , Baptiste Jeudy1 of graph mining for tracking objects in videos with moving cameras and without any contextual information on the objects to track. To make the mining algorithm efficient, we benefit from a video representation based

  16. A tree-decomposed transfer matrix for computing exact Potts model partition functions for arbitrary graphs, with applications to planar graph colourings

    E-Print Network [OSTI]

    Andrea Bedini; Jesper Lykke Jacobsen

    2010-08-06T23:59:59.000Z

    Combining tree decomposition and transfer matrix techniques provides a very general algorithm for computing exact partition functions of statistical models defined on arbitrary graphs. The algorithm is particularly efficient in the case of planar graphs. We illustrate it by computing the Potts model partition functions and chromatic polynomials (the number of proper vertex colourings using Q colours) for large samples of random planar graphs with up to N=100 vertices. In the latter case, our algorithm yields a sub-exponential average running time of ~ exp(1.516 sqrt(N)), a substantial improvement over the exponential running time ~ exp(0.245 N) provided by the hitherto best known algorithm. We study the statistics of chromatic roots of random planar graphs in some detail, comparing the findings with results for finite pieces of a regular lattice.

  17. Bond Graph Modeling of Current Diffusion in Magnetic Cores Herv Morel, Bruno Allard, Sabrine M'Rad, Cyril Buttay

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Bond Graph Modeling of Current Diffusion in Magnetic Cores Hervé Morel, Bruno Allard, Sabrine M, F-69621 Villeurbanne Cedex, France KEYBOARD: Bond Graphs, Variational approximation, Diffusive with the diffusion representation. Both approaches yield a same bond graph representation. 2. MODELING CURRENT

  18. A framework for graph-based synthesis, analysis, and visualization of HPC cluster job data.

    SciTech Connect (OSTI)

    Mayo, Jackson R.; Kegelmeyer, W. Philip, Jr.; Wong, Matthew H.; Pebay, Philippe Pierre; Gentile, Ann C.; Thompson, David C.; Roe, Diana C.; De Sapio, Vincent; Brandt, James M.

    2010-08-01T23:59:59.000Z

    The monitoring and system analysis of high performance computing (HPC) clusters is of increasing importance to the HPC community. Analysis of HPC job data can be used to characterize system usage and diagnose and examine failure modes and their effects. This analysis is not straightforward, however, due to the complex relationships that exist between jobs. These relationships are based on a number of factors, including shared compute nodes between jobs, proximity of jobs in time, etc. Graph-based techniques represent an approach that is particularly well suited to this problem, and provide an effective technique for discovering important relationships in job queuing and execution data. The efficacy of these techniques is rooted in the use of a semantic graph as a knowledge representation tool. In a semantic graph job data, represented in a combination of numerical and textual forms, can be flexibly processed into edges, with corresponding weights, expressing relationships between jobs, nodes, users, and other relevant entities. This graph-based representation permits formal manipulation by a number of analysis algorithms. This report presents a methodology and software implementation that leverages semantic graph-based techniques for the system-level monitoring and analysis of HPC clusters based on job queuing and execution data. Ontology development and graph synthesis is discussed with respect to the domain of HPC job data. The framework developed automates the synthesis of graphs from a database of job information. It also provides a front end, enabling visualization of the synthesized graphs. Additionally, an analysis engine is incorporated that provides performance analysis, graph-based clustering, and failure prediction capabilities for HPC systems.

  19. A note on QUBO instances defined on Chimera graphs

    E-Print Network [OSTI]

    Sanjeeb Dash

    2013-07-01T23:59:59.000Z

    McGeoch and Wang (2013) recently obtained optimal or near-optimal solutions to some quadratic unconstrained boolean optimization (QUBO) problem instances using a 439 qubit D-Wave Two quantum computing system in much less time than with the IBM ILOG CPLEX mixed-integer quadratic programming (MIQP) solver. The problems studied by McGeoch and Wang are defined on subgraphs -- with up to 439 nodes -- of Chimera graphs. We observe that after a standard reformulation of the QUBO problem as a mixed-integer linear program (MILP), the specific instances used by McGeoch and Wang can be solved to optimality with the CPLEX MILP solver in much less time than the time reported in McGeoch and Wang for the CPLEX MIQP solver. However, the solution time is still more than the time taken by the D-Wave computer in the McGeoch-Wang tests.

  20. Linking SARAH and MadGraph using the UFO format

    E-Print Network [OSTI]

    Staub, Florian

    2012-01-01T23:59:59.000Z

    SARAH is a Mathematica package optimized for the fast, efficient and precise study of supersymmetric models beyond the MSSM: a new model can be defined in a short form and all vertices are derived. This allows SARAH to create model files for FeynArts/FormCalc, CalcHep/CompHep and WHIZARD/OMEGA. The newest version of SARAH now provides the possibility to create model files in the UFO format which is supported by MadGraph 5, MadAnalysis 5, GoSam, and soon by Herwig++. Furthermore, SARAH also calculates the mass matrices, RGEs and 1-loop corrections to the mass spectrum. This information is used to write source code for SPheno in order to create a precision spectrum generator for the given model. This spectrum-generator-generator functionality as well as the output of WHIZARD and CalcHep model files have seen further improvement in this version.

  1. A PTAS for the Classical Ising Spin Glass Problem on the Chimera Graph Structure

    E-Print Network [OSTI]

    Rishi Saket

    2013-07-01T23:59:59.000Z

    We present a polynomial time approximation scheme (PTAS) for the minimum value of the classical Ising Hamiltonian with linear terms on the Chimera graph structure as defined in the recent work of McGeoch and Wang. The result follows from a direct application of the techniques used by Bansal, Bravyi and Terhal who gave a PTAS for the same problem on planar and, in particular, grid graphs. We also show that on Chimera graphs, the trivial lower bound is within a constant factor of the optimum.

  2. Graph fusion algebras of WLM(p,p')

    E-Print Network [OSTI]

    Jorgen Rasmussen

    2010-01-14T23:59:59.000Z

    We consider the W-extended logarithmic minimal model WLM(p,p'). As in the rational minimal models, the so-called fundamental fusion algebra of WLM(p,p') is described by a simple graph fusion algebra. The fusion matrices in the regular representation thereof are mutually commuting, but in general not diagonalizable. Nevertheless, we show that they can be brought simultaneously to block-diagonal forms whose blocks are upper-triangular matrices of dimension 1, 3, 5 or 9. The directed graphs associated with the two fundamental modules are described in detail. The corresponding adjacency matrices share a complete set of common generalized eigenvectors organized as a web constructed by interlacing the Jordan chains of the two matrices. This web is here called a Jordan web and it consists of connected subwebs with 1, 3, 5 or 9 generalized eigenvectors. The similarity matrix, formed by concatenating these vectors, simultaneously brings the two fundamental adjacency matrices to Jordan canonical form modulo permutation similarity. The ranks of the participating Jordan blocks are 1 or 3, and the corresponding eigenvalues are given by 2cos(j\\pi/n) where j=0,...,n and n=p,p'. For p>1, only some of the modules in the fundamental fusion algebra of WLM(p,p') are associated with boundary conditions within our lattice approach. The regular representation of the corresponding fusion subalgebra has features similar to the ones in the regular representation of the fundamental fusion algebra, but with dimensions of the upper-triangular blocks and connected Jordan-web components given by 1, 2, 3 or 8. Some of the key results are illustrated for W-extended critical percolation WLM(2,3).

  3. Feedback vertex sets and disjoint cycles in planar (di)graphs

    E-Print Network [OSTI]

    graph has a feedback vertex set of cardinality at most k then its treewidth. is bounded ... in linear time, and this is used to nd an algorithm computing a feedback.

  4. Dynamic Distributed Multimedia: Seamless Sharing and Reconfiguration of Multimedia Flow Graphs

    E-Print Network [OSTI]

    Lohse, Marco

    Dynamic Distributed Multimedia: Seamless Sharing and Reconfiguration of Multimedia Flow Graphs Abstract Mobile devices with multimedia and networking capabilities are quickly becoming ubiquitous through the availability of small note- books, PDA, and in particular, mobile phones. However, most multimedia systems

  5. Forced Orientation of Graphs B. FARZAD , M. MAHDIAN y , E.S. MAHMOODIAN z ,

    E-Print Network [OSTI]

    Saberi, Amin

    Forced Orientation of Graphs B. FARZAD #3; , M. MAHDIAN y , E.S. MAHMOODIAN z , A. SABERI x , AND B, Georgia Institute of Technology, Atlanta, USA. (saberi@cc.gatech.edu) { Department of Computer Science

  6. Homogeneous Factorisations of Graphs and Michael Giudici a, Cai Heng Li a

    E-Print Network [OSTI]

    Giudici, Michael

    Homogeneous Factorisations of Graphs and Digraphs Michael Giudici a, Cai Heng Li a Primoz Potocnik@maths.uwa.edu.au (Michael Giudici), li@maths.uwa.edu.au (Cai Heng Li), primoz.potocnik@fmf.uni-lj.si (Primoz Preprint

  7. Omega: an Overlap-graph de novo Assembler for Meta-genomics

    SciTech Connect (OSTI)

    Haider, Bahlul [ORNL; Ahn, Tae-Hyuk [ORNL; Bushnell, Brian [U.S. Department of Energy, Joint Genome Institute; Chai, JJ [ORNL; Copeland, Alex [U.S. Department of Energy, Joint Genome Institute; Pan, Chongle [ORNL

    2014-01-01T23:59:59.000Z

    Motivation: Metagenomic sequencing allows reconstruction of mi-crobial genomes directly from environmental samples. Omega (overlap-graph metagenome assembler) was developed here for assembling and scaffolding Illumina sequencing data of microbial communities. Results: Omega found overlaps between reads using a prefix/suffix hash table. The overlap graph of reads was simplified by removing transitive edges and trimming small branches. Unitigs were generat-ed based on minimum cost flow analysis of the overlap graph. Obtained unitigs were merged to contigs and scaffolds using mate-pair information. Omega was compared with two de Bruijn graph assemblers, SOAPdenovo and IDBA-UD, using a publically-available Illumina sequencing dataset of a 64-genome mock com-munity. The assembly results were verified by their alignment with reference genomes. The overall performances of the three assem-blers were comparable and each assembler provided best results for a subset of genomes.

  8. Continuous-Time Intruder Isolation Using Unattended Ground Sensors on a General Graph

    E-Print Network [OSTI]

    Zhang, Wei

    Continuous-Time Intruder Isolation Using Unattended Ground Sensors on a General Graph Hua Chen by several Unattended Ground Sensors (UGSs). The intruder is assumed to travel on a road network

  9. A Genetic Algorithm Applied to Graph Problems Involving Subsets of Vertices

    E-Print Network [OSTI]

    Wainwright, Roger L.

    and Computer Sciences University of Tulsa University of Tulsa 600 South College Avenue 600 South College Avenue Tulsa, OK 74104 USA Tulsa, OK 74104 USA rogerw@utulsa.edu Abstract - Many graph problems seek subsets

  10. Partitioning 2-edge-colored Ore-type graphs by monochromatic cycles

    E-Print Network [OSTI]

    Sarkozy, Gabor

    . A more elementary proof, still for large enough n, was obtained by Allen [1]. Finally, Bessy and Thomass, the above mentioned Bessy-Thomass´e result [5] would hold for graphs with minimum degree larger than 3n/4

  11. THE SPECTRAL RADIUS OF INFINITE GRAPHS N. L. BIGGS, BOJAN MOHAR AND JOHN SHAWE-TAYLOR

    E-Print Network [OSTI]

    Mohar, Bojan

    THE SPECTRAL RADIUS OF INFINITE GRAPHS N. L. BIGGS, BOJAN MOHAR AND JOHN SHAWE-TAYLOR 1 follows from Theorem 2.2. #12;118 N. L. BIGGS, B. MOHAR AND J. SHAWE-TAYLOR 3. The expanding case

  12. A New Approach to Argument by Analogy: Extrapolation and Chain Graphs Daniel Steel

    E-Print Network [OSTI]

    Steel, Daniel

    A New Approach to Argument by Analogy: Extrapolation and Chain Graphs Daniel Steel Department of Philosophy 503 S Kedzie Hall East Lansing, MI 48824-1032 steel@msu.edu #12;1. Introduction. In order to make

  13. The usefulness of the generalised computational model of Term Graph Rewriting Systems (TGRS) for designing and

    E-Print Network [OSTI]

    Banach, Richard

    of programs written in UFO ([8,9]), a state-of-the-art object- oriented functional language, onto equivalent as follows: the next two sections introduce MONSTR and UFO and provide Term Graph Rewriting

  14. Storage device sizing for a hybrid railway traction system by means of bicausal bond graphs

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    (a supercapacitor) included in this system is then discussed. Keywords: bond graph, bicausality In the paper, the example of a supercapacitor process consists of choosing the system structure dimensioning

  15. The Effect of Graph Layout on Inference from Social Network Data

    E-Print Network [OSTI]

    Blythe, Jim

    The Effect of Graph Layout on Inference from Social Network Data Jim Blythe 1 and Cathleen Mc of information to be #12; Ivo Jack Ben York Earl Rick Mel Dale Robin Nan Gerry Bob Fran Walt Ovid Gary Chris Hugh

  16. Coloring Kk-free intersection graphs of geometric objects in the plane

    E-Print Network [OSTI]

    Fox, Jacob

    Coloring Kk-free intersection graphs of geometric objects in the plane Jacob Fox Department that copies are not made or distributed for profit or commercial advantage and that copies bear this notice

  17. Complete solution to a conjecture on the maximal energy of unicyclic graphs

    E-Print Network [OSTI]

    Huo, Bofeng; Shi, Yongtang

    2010-01-01T23:59:59.000Z

    For a given simple graph $G$, the energy of $G$ denoted by $E(G)$, is defined as the sum of the absolute values of all eigenvalues of its adjacency matrix. Let $P_n^{\\ell}$ be the unicyclic graph obtained by connecting a vertex of $C_\\ell$ with a leaf of $P_{n-\\ell}$\\,. In [G. Caporossi, D. Cvetkovi\\'c, I. Gutman, P. Hansen, Variable neighborhood search for extremal graphs. 2. Finding graphs with extremal energy, {\\it J. Chem. Inf. Comput. Sci.\\/} {\\bf 39} (1999) 984--996], Caporossi et al. conjectured that the unicyclic graph with maximal energy is $C_n$ if $n\\leq 7$ and $n=9,10,11,13,15$\\,, and $P_n^6$ for all other values of $n$. In this paper, by employing the Coulson integral formula and some knowledge of real analysis, especially by using certain combinatorial techniques, we completely solve this conjecture. However, it turns out that for $n=4$ the conjecture is not true, and $P_4^3$ should be the unicyclic graph with maximal energy.

  18. Exact sampling of graphs with prescribed degree correlations

    E-Print Network [OSTI]

    Bassler, Kevin E; Erd?s, Péter L; Miklós, István; Toroczkai, Zoltán

    2015-01-01T23:59:59.000Z

    Many real-world networks exhibit correlations between the node degrees. For instance, in social networks nodes tend to connect to nodes of similar degree. Conversely, in biological and technological networks, high-degree nodes tend to be linked with low-degree nodes. Degree correlations also affect the dynamics of processes supported by a network structure, such as the spread of opinions or epidemics. The proper modelling of these systems, i.e., without uncontrolled biases, requires the sampling of networks with a specified set of constraints. We present a solution to the sampling problem when the constraints imposed are the degree correlations. In particular, we develop an efficient and exact method to construct and sample graphs with a specified joint-degree matrix, which is a matrix providing the number of edges between all the sets of nodes of a given degree, for all degrees, thus completely specifying all pairwise degree correlations, and additionally, the degree sequence itself. Our algorithm always pro...

  19. How the permutation of edges of a metric graph affects the number of points moving along the edges

    E-Print Network [OSTI]

    V. L. Chernyshev; A. A. Tolchennikov

    2014-10-18T23:59:59.000Z

    We consider a dynamical system on a metric graph, that corresponds to a semiclassical solution of a time-dependent Schr\\"odinger equation. We omit all details concerning mathematical physics and work with a purely discrete problem. We find a weak inequality representation for the number of points coming out of the vertex of an arbitrary tree graph. We apply this construction to an "H-junction" graph. We calculate the difference between numbers of moving points corresponding to the permutation of edges. Then we find a symmetrical difference of the number of points moving along the edges of a metric graph.

  20. Hierarchical graphs for better annotations of rule-based models of biochemical systems

    SciTech Connect (OSTI)

    Hu, Bin [Los Alamos National Laboratory; Hlavacek, William [Los Alamos National Laboratory

    2009-01-01T23:59:59.000Z

    In the graph-based formalism of the BioNetGen language (BNGL), graphs are used to represent molecules, with a colored vertex representing a component of a molecule, a vertex label representing the internal state of a component, and an edge representing a bond between components. Components of a molecule share the same color. Furthermore, graph-rewriting rules are used to represent molecular interactions, with a rule that specifies addition (removal) of an edge representing a class of association (dissociation) reactions and with a rule that specifies a change of vertex label representing a class of reactions that affect the internal state of a molecular component. A set of rules comprises a mathematical/computational model that can be used to determine, through various means, the system-level dynamics of molecular interactions in a biochemical system. Here, for purposes of model annotation, we propose an extension of BNGL that involves the use of hierarchical graphs to represent (1) relationships among components and subcomponents of molecules and (2) relationships among classes of reactions defined by rules. We illustrate how hierarchical graphs can be used to naturally document the structural organization of the functional components and subcomponents of two proteins: the protein tyrosine kinase Lck and the T cell receptor (TCR)/CD3 complex. Likewise, we illustrate how hierarchical graphs can be used to document the similarity of two related rules for kinase-catalyzed phosphorylation of a protein substrate. We also demonstrate how a hierarchical graph representing a protein can be encoded in an XML-based format.

  1. Fusion categories in terms of graphs and relations

    E-Print Network [OSTI]

    Hendryk Pfeiffer

    2011-04-20T23:59:59.000Z

    Every fusion category C that is k-linear over a suitable field k, is the category of finite-dimensional comodules of a Weak Hopf Algebra H. This Weak Hopf Algebra is finite-dimensional, cosemisimple and has commutative bases. It arises as the universal coend with respect to the long canonical functor \\omega:C->Vect_k. We show that H is a quotient H=H[G]/I of a Weak Bialgebra H[G] which has a combinatorial description in terms of a finite directed graph G that depends on the choice of a generator M of C and on the fusion coefficients of C. The algebra underlying H[G] is the path algebra of the quiver GxG, and so the composability of paths in G parameterizes the truncation of the tensor product of C. The ideal I is generated by two types of relations. The first type enforces that the tensor powers of the generator M have the appropriate endomorphism algebras, thus providing a Schur-Weyl dual description of C. If C is braided, this includes relations of the form `RTT=TTR' where R contains the coefficients of the braiding on \\omega M\\otimes\\omega M, a generalization of the construction of Faddeev-Reshetikhin-Takhtajan to Weak Bialgebras. The second type of relations removes a suitable set of group-like elements in order to make the category of finite-dimensional comodules equivalent to C over all tensor powers of the generator M. As examples, we treat the modular categories associated with U_q(sl_2).

  2. Decay of Correlations for the Hardcore Model on the $d$-regular Random Graph

    E-Print Network [OSTI]

    Nayantara Bhatnagar; Allan Sly; Prasad Tetali

    2014-05-23T23:59:59.000Z

    A key insight from statistical physics about spin systems on random graphs is the central role played by Gibbs measures on trees. We determine the local weak limit of the hardcore model on random regular graphs asymptotically until just below its condensation threshold, showing that it converges in probability locally in a strong sense to the free boundary condition Gibbs measure on the tree. As a consequence we show that the reconstruction threshold on the random graph, indicative of the onset of point to set spatial correlations, is equal to the reconstruction threshold on the $d$-regular tree for which we determine precise asymptotics. We expect that our methods will generalize to a wide range of spin systems for which the second moment method holds.

  3. Analyzing the Facebook friendship graph S. Catanese1, P. De Meo2, E. Ferrara3, G. Fiumara1

    E-Print Network [OSTI]

    Ferrara, Emilio

    Analyzing the Facebook friendship graph S. Catanese1, P. De Meo2, E. Ferrara3, G. Fiumara1 1Dept Internet 20 September 2010, Berlin Catanese, De Meo, Ferrara, Fiumara () Analyzing the Facebook friendship Issues Catanese, De Meo, Ferrara, Fiumara () Analyzing the Facebook friendship graph MIFI 2010, 20

  4. DYNAMIC CONFIGURATION OF DATAFLOW GRAPH TOPOLOGY FOR DSP SYSTEM DESIGN Dong-Ik Ko and Shuvra S. Bhattacharyya

    E-Print Network [OSTI]

    Bhattacharyya, Shuvra S.

    DYNAMIC CONFIGURATION OF DATAFLOW GRAPH TOPOLOGY FOR DSP SYSTEM DESIGN Dong-Ik Ko and Shuvra S dynamic port can keep the model bounded. However, control flow depends on FSMs. Using FSMs for minor changes of control flow with data- flow graphs can make application models unnecessarily compli- cated

  5. GeoTriples: a Tool for Publishing Geospatial Data as RDF Graphs Using R2RML Mappings

    E-Print Network [OSTI]

    Koubarakis, Manolis

    GeoTriples: a Tool for Publishing Geospatial Data as RDF Graphs Using R2RML Mappings Kostis the linked data paradigm. Therefore, Earth Ob- servation data and other kinds of geospatial data and geospatial data into RDF graphs. GeoTriples goes beyond the state of the art by extending the R2RML mapping

  6. In "Handbook of Mathematical Models in Computer Vision", Springer, 2006 p.1 Graph Cuts in Vision and Graphics

    E-Print Network [OSTI]

    Boykov, Yuri

    and Graphics: Theories and Applications Yuri Boykov and Olga Veksler Computer Science, The University the corresponding graph. Thus, many applications in vision and graphics use min-cut algorithms as a tool for computing optimal hypersurfaces. Secondly, graph-cuts also work as a powerful energy minimization tool

  7. 17Solar Storm Energy and Pie Graphs The pie charts below show approximately how various forms of energy

    E-Print Network [OSTI]

    17Solar Storm Energy and Pie Graphs The pie charts below show approximately how various forms of energy are involved in a solar flare. Flares occur when stored magnetic energy is suddenly released magnetic energy Graph of solar flare energy forms Problem 1 - About what percentages of each of the four

  8. ON TIMED EVENT GRAPH STABILIZATION BY OUTPUT FEEDBACK IN DIOID Bertrand Cottenceau, Laurent Hardouin, Jean-Louis Boimond 1

    E-Print Network [OSTI]

    Boyer, Edmond

    synthesis for Timed Event Graphs (TEG) in dioid algebra. The feedback synthesis is done in order to stabilize a TEG without decreasing its original production rate, optimize the initial marking Event Graphs (TEG) stabilization. We rst recall that a TEG is a Petri net whose each place has one

  9. Pictures of Processes: Automated Graph Rewriting for Monoidal Categories and Applications to Quantum Computing

    E-Print Network [OSTI]

    Aleks Kissinger

    2012-03-22T23:59:59.000Z

    This work is about diagrammatic languages, how they can be represented, and what they in turn can be used to represent. More specifically, it focuses on representations and applications of string diagrams. String diagrams are used to represent a collection of processes, depicted as "boxes" with multiple (typed) inputs and outputs, depicted as "wires". If we allow plugging input and output wires together, we can intuitively represent complex compositions of processes, formalised as morphisms in a monoidal category. [...] The first major contribution of this dissertation is the introduction of a discretised version of a string diagram called a string graph. String graphs form a partial adhesive category, so they can be manipulated using double-pushout graph rewriting. Furthermore, we show how string graphs modulo a rewrite system can be used to construct free symmetric traced and compact closed categories on a monoidal signature. The second contribution is in the application of graphical languages to quantum information theory. We use a mixture of diagrammatic and algebraic techniques to prove a new classification result for strongly complementary observables. [...] We also introduce a graphical language for multipartite entanglement and illustrate a simple graphical axiom that distinguishes the two maximally-entangled tripartite qubit states: GHZ and W. [...] The third contribution is a description of two software tools developed in part by the author to implement much of the theoretical content described here. The first tool is Quantomatic, a desktop application for building string graphs and graphical theories, as well as performing automated graph rewriting visually. The second is QuantoCoSy, which performs fully automated, model-driven theory creation using a procedure called conjecture synthesis.

  10. Automation of the Dipole Subtraction Method in MadGraph/MadEvent

    E-Print Network [OSTI]

    Rikkert Frederix; Thomas Gehrmann; Nicolas Greiner

    2008-08-15T23:59:59.000Z

    We present the implementation of the dipole subtraction formalism for the real radiation contributions to any next-to-leading order QCD process in the MadGraph/MadEvent framework. Both massless and massive dipoles are considered. Starting from a specific (n+1)-particle process the package provides a Fortran code for all possible dipoles to all Born processes that constitute the subtraction term to the (n+1)-particle process. The output files are given in the usual "MadGraph StandAlone" style using helicity amplitudes.

  11. Multiclass Diffuse Interface Models for Semi-Supervised Learning on Graphs

    E-Print Network [OSTI]

    Garcia-Cardona, Cristina; Percus, Allon G

    2012-01-01T23:59:59.000Z

    We present a graph-based variational algorithm for multiclass classification of high-dimensional data, motivated by total variation techniques. The energy functional is based on a diffuse interface model with a periodic potential. We augment the model by introducing an alternative measure of smoothness that preserves symmetry among the class labels. Through this modification of the standard Laplacian, we construct an efficient multiclass method that allows for sharp transitions between classes. The experimental results demonstrate that our approach is competitive with the state of the art among other graph-based algorithms.

  12. Improved vertex cover algorithms for fixed genus graphs through genus reduction and planar separation

    E-Print Network [OSTI]

    Gupton, Kevin Thomas

    2003-01-01T23:59:59.000Z

    , problems are restricted to decision problems? problems with yes/no answers. The VERTEX CovER problem formulated as a decision problem is "Given a graph G = (V, E) and positive cover k, does there exist a vertex cover of G whose size is at most k...: "Given a graph G = (V, E) and parameter k, does there exist a vertex cover C c: V for G such that C~ & k?" As a decision problem, Karp first demonstrated quantitatively how "hard" VERTEx CovER is to solve by showing that vERTEx covER is NP-complete [16...

  13. Non maximal cyclically monotone graphs and construction of a bipotential for the Coulomb's dry friction law

    E-Print Network [OSTI]

    Buliga, Marius; Vallee, Claude

    2008-01-01T23:59:59.000Z

    We show a surprising connexion between a property of the inf convolutions of a family of convex lower semicontinuous functions and the fact that intersections of maximal cyclically monotone graphs are the critical set of a bipotential. We then extend the results from arXiv:math/0608424v4 to bipotentials convex covers, generalizing the notion of a bi-implicitly convex lagrangian cover. As an application we prove that the bipotential related to Coulomb's friction law is related to a specific bipotential convex cover with the property that any graph of the cover is non maximal cyclically monotone.

  14. A novel configuration model for random graphs with given degree sequence

    E-Print Network [OSTI]

    Xinping Xu; Feng Liu

    2007-08-20T23:59:59.000Z

    Recently, random graphs in which vertices are characterized by hidden variables controlling the establishment of edges between pairs of vertices have attracted much attention. Here, we present a specific realization of a class of random network models in which the connection probability between two vertices (i,j) is a specific function of degrees ki and kj. In the framework of the configuration model of random graphs, we find analytical expressions for the degree correlation and clustering as a function of the variance of the desired degree distribution. The expressions obtained are checked by means of numerical simulations. Possible applications of our model are discussed.

  15. Quantum Secret Sharing with Graph States Sylvain Gravier1,2, Jer^ome Javelle3, Mehdi Mhalla1,3, and Simon Perdrix1,3

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Quantum Secret Sharing with Graph States Sylvain Gravier1,2, J´er^ome Javelle3, Mehdi Mhalla1 study the graph-state-based quantum secret sharing protocols [24, 17] which are not only very promising on the graphical characterization of the graph-state-based secret shar- ing properties, in particular we point out

  16. The Power of Team Exploration: Two Robots Can Learn Unlabeled Directed Graphs

    E-Print Network [OSTI]

    Bender, Michael

    The Power of Team Exploration: Two Robots Can Learn Unlabeled Directed Graphs Michael A. Bender communicate freely by radio. Radio communication is used to synchro­ nize actions. If we assume that the two robots move synchronously and share a polynomial­length random string, then no communication is necessary

  17. LOOP TRANSFORMATIONS FOR INTERFACE-BASED HIERARCHIES IN SDF GRAPHS Jonathan Piat1

    E-Print Network [OSTI]

    Bhattacharyya, Shuvra S.

    LOOP TRANSFORMATIONS FOR INTERFACE-BASED HIERARCHIES IN SDF GRAPHS Jonathan Piat1 , Shuvra S processing (DSP) applica- tions. A restricted version of data-flow, termed synchronous data-flow (SDF of hierarchy (Interface-based SDF) has been proposed allowing more expressivity while maintaining its

  18. Back to Basics: Homogeneous Representations of Multi-Rate Synchronous Dataflow Graphs

    E-Print Network [OSTI]

    Al Hanbali, Ahmad

    Synchronous dataflow (SDF) [1] is a popular class of models of computation and is used to model the temporal are particularly useful in the design of systems where worst-case guarantees on performance must be given. An SDF and processing elements. The class of SDF graphs that we focus on in this paper are called multi-rate SDF (MRSDF

  19. Improved Steiner Tree Approximation in Graphs Gabriel Robins \\Lambda Alexander Zelikovsky y

    E-Print Network [OSTI]

    Zelikovsky, Alexander

    ). In quasi­bipartite graphs our heuristic achieves an approximation ratio of ß 1:28 in time O(mn 2 ), where m also show \\Lambda Department of Computer Science, University of Virginia, Thornton Hall, Charlottesville, VA, 22903, robins@cs.virginia.edu y Department of Computer Science, Georgia State University

  20. Factor Graphs for Universal Portfolios Andrew J. Bean and Andrew C. Singer

    E-Print Network [OSTI]

    Singer, Andrew C

    transaction costs while taking advantage of side information. We introduce factor graphs as a computational of sequentially investing in a stock market where we have access to a side information sequence and we also must the ratio of the opening price of the jth stock on the (t + 1)th trading period to the opening price

  1. Artificial Intelligence 135 (2002) 73123 Planning graph as the basis for deriving heuristics

    E-Print Network [OSTI]

    Kambhampati, Subbarao

    2002-01-01T23:59:59.000Z

    families of heuristics, some aimed at search speed and others at optimality of solutions, and analyze many search, we describe a novel way of using the planning graph structure to derive highly effective variable explicitly search in the space of world states. Their superior performance comes from the heuristic

  2. Non-perturbative corrections to mean-field behavior: spherical model on spider-web graph

    E-Print Network [OSTI]

    Ajit C. Balram; Deepak Dhar

    2012-02-09T23:59:59.000Z

    We consider the spherical model on a spider-web graph. This graph is effectively infinite-dimensional, similar to the Bethe lattice, but has loops. We show that these lead to non-trivial corrections to the simple mean-field behavior. We first determine all normal modes of the coupled springs problem on this graph, using its large symmetry group. In the thermodynamic limit, the spectrum is a set of $\\delta$-functions, and all the modes are localized. The fractional number of modes with frequency less than $\\omega$ varies as $\\exp (-C/\\omega)$ for $\\omega$ tending to zero, where $C$ is a constant. For an unbiased random walk on the vertices of this graph, this implies that the probability of return to the origin at time $t$ varies as $\\exp(- C' t^{1/3})$, for large $t$, where $C'$ is a constant. For the spherical model, we show that while the critical exponents take the values expected from the mean-field theory, the free-energy per site at temperature $T$, near and above the critical temperature $T_c$, also has an essential singularity of the type $\\exp[ -K {(T - T_c)}^{-1/2}]$.

  3. Predicting Protein Folds with Structural Repeats Using a Chain Graph Model

    E-Print Network [OSTI]

    Xing, Eric P.

    Predicting Protein Folds with Structural Repeats Using a Chain Graph Model Yan Liu yanliu, Carnegie Mellon University, Pittsburgh, PA 15213 USA Abstract Protein fold recognition is a key step to to accurately identify protein folds aris- ing from typical spatial arrangements of well-defined secondary

  4. Flexible Graph Layout for the Web Trevor Hansen, Kim Marriott & Bernd Meyer

    E-Print Network [OSTI]

    Marriott, Kimbal

    and is manifest in almost all web standards from the HTML/CSS [1] combination to XML/XSL [6, 23]. Recent graphics bandwidth has meant that graphics has become increasingly important on the web. Graph-based dia- grams are one of the most important types of structured graphical information. Here we demonstrate how XML can

  5. Semantics Guided Filtering of Combinatorial Graph Transformations in Declarative Equation-Based Languages.

    E-Print Network [OSTI]

    Burns, Peter

    required to get the simulation working. The paper is organized as follows: Section 2 introduces Modelica, a new equation-based declarative language. Some specific Modelica language constructs necessary using Modelica. Section 5 gives some preliminary definitions related to the concept of bipartite graphs

  6. Geosocial Graph-Based Community Detection Yves van Gennip, Huiyi Hu, Blake Hunter

    E-Print Network [OSTI]

    Soatto, Stefano

    geosocial information. The data come from the policing district Hollenbeck (see Fig. 1) in Los AngelesGeosocial Graph-Based Community Detection Yves van Gennip, Huiyi Hu, Blake Hunter Department of Mathematics University of California, Los Angeles Los Angeles, CA, USA Email: yvgennip@math.ucla.edu, huiyihu

  7. GRAPH-BASED METHOD FOR MULTITEMPORAL SEGMENTATION OF SEA ICE FLOES FROM SATELLITE DATA

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    the Arc- tic sea ice pack in December 2007, continuously moved with the Arctic ocean currents and meltedGRAPH-BASED METHOD FOR MULTITEMPORAL SEGMENTATION OF SEA ICE FLOES FROM SATELLITE DATA Claudio, MODIS, Sea Ice Floes. ABSTRACT: Automated segmentation of the sea ice evolution would allow scientists

  8. Data mining in an engineering design environment: OR applications from graph matching1

    E-Print Network [OSTI]

    Nagi, Rakesh

    1 Data mining in an engineering design environment: OR applications from graph matching1 Carol J York 14623 Abstract Data mining has been making inroads into the engineering design environment ­ an area that generates large amounts of heterogeneous data for which suitable mining methods

  9. Finite propagation speed for solutions of the wave equation on metric graphs

    E-Print Network [OSTI]

    Vadim Kostrykin; Jürgen Potthoff; Robert Schrader

    2011-06-04T23:59:59.000Z

    We provide a class of self-adjoint Laplace operators on metric graphs with the property that the solutions of the associated wave equation satisfy the finite propagation speed property. The proof uses energy methods, which are adaptions of corresponding methods for smooth manifolds.

  10. Interactive Separation of Segmented Bones in CT Volumes Using Graph Cut

    E-Print Network [OSTI]

    Ju, Tao

    mask customized to the shape of the bone, such as the femoral head. However, creat- ing masks for bones of different methodology have been reported for bone segmen- tation (see a recent survey in [1]). DueInteractive Separation of Segmented Bones in CT Volumes Using Graph Cut Lu Liu, David Raber, David

  11. First Steps toward Automated Design of Mechatronic Systems Using Bond Graphs and Genetic Programming

    E-Print Network [OSTI]

    Fernandez, Thomas

    , mechanical, hydraulic, pneumatic, and thermal components, making it difficult to design a system to meetFirst Steps toward Automated Design of Mechatronic Systems Using Bond Graphs and Genetic@egr.msu.edu 1 OVERVIEW OF THE WORK This paper suggests a method for automatically synthesizing designs

  12. Bond Graph Modeling of Centrifugal Compressor System Nur Uddin and Jan Tommy Gravdahl

    E-Print Network [OSTI]

    Gravdahl, Jan Tommy

    Bond Graph Modeling of Centrifugal Compressor System Nur Uddin and Jan Tommy Gravdahl Dept, Norway N-7491 nur.uddin@itk.ntnu.no, Jan.Tommy.Gravdahl@itk.ntnu.no Keywords: Compressor, compressor. A model of a compression system with recycle flow is derived in this work. 1. INTRODUCTION Compressors

  13. Novel approaches for solving large-scale optimization problems on graphs

    E-Print Network [OSTI]

    Trukhanov, Svyatoslav

    2009-05-15T23:59:59.000Z

    . . . . . . . . . . . . . . . . . . . . . . . 97 8 Parameters of calculated weighted diversified portfolios correspon- ding to 500-day trading periods . . . . . . . . . . . . . . . . . . . . . 110 9 Graph parameters for small test-bed . . . . . . . . . . . . . . . . . . 126 10 Number of k... . . . . . . . . . . . . . . . . . . 29 5 Crown structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 6 t-hat structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 7 2-club and 2-clique example . . . . . . . . . . . . . . . . . . . . . . . 54 8...

  14. Modeling and Control for Balanced Timed and Weighted Event Graphs in Dioids

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Modeling and Control for Balanced Timed and Weighted Event Graphs in Dioids Bertrand Cottenceau for which some model matching control problems have been solved. In the context of manufacturing applications, the controllers obtained by these approaches have the effect of regulating material flows

  15. On Reducing the Global State Graph for Verification of Distributed Computations

    E-Print Network [OSTI]

    Garg, Vijay

    On Reducing the Global State Graph for Verification of Distributed Computations Arindam Chakraborty and Vijay K. Garg Parallel and Distributed Systems Laboratory The University of Texas at Austin Austin, TX 78712, USA {chakrabo,garg}@ece.utexas.edu Abstract Correct distributed programs are very hard to write

  16. Optimizing Graph Algorithms for Improved Cache Performance*+ Joon-Sang Park

    E-Print Network [OSTI]

    Prasanna, Viktor K.

    . For these algorithms, we demonstrate up to 2Ã? improvement in real execution time by using a simple cache- friendly graphs. We show performance improvements of 2Ã? - 3Ã? in real execution time by using the technique N and C are the problem size and cache size respectively. Experimental results show that this cache

  17. A Genetic Algorithm based Approach for Multi-Objective Data-Flow Graph Optimization

    E-Print Network [OSTI]

    Coello, Carlos A. Coello

    that the correct- ness of algebraic transformations realized by the underlying genetic operators selection shown for power optimization. In order to avoid inferior results caused by the counteracting demandsA Genetic Algorithm based Approach for Multi-Objective Data-Flow Graph Optimization Birger Landwehr

  18. Evaluation of Semantic Graph based on Model Checking Mahdi Gueffaz, Sylvain Rampacek and Christophe Nicolle

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    floods. Model checking is a powerful tool for system verification because it can reveal errors that were to describe the properties checking the system model. 395 hal-00617998,version1-31Aug2011 Author manuscriptSCALESEM Evaluation of Semantic Graph based on Model Checking Mahdi Gueffaz, Sylvain Rampacek

  19. Margin based Transductive Graph Cuts using Linear Programming K. Pelckmans(1)

    E-Print Network [OSTI]

    , and is subsequently related to the classical MINCUT approach. From a practical perspective a simple and intu- itive clustering. Keywords: Graph Cuts, Transductive Inference, Statistical Learning, Clustering, Combinatorial research witnessed a renewed surge of interest in the MINCUT problem, culminating in the theoretical

  20. A Graph-based Approach to API Usage Adaptation Hoan Anh Nguyen,1a

    E-Print Network [OSTI]

    Kim, Miryung

    to accommodate new feature requests, to fix bugs, and to meet new standards, changes in API declarationsA Graph-based Approach to API Usage Adaptation Hoan Anh Nguyen,1a Tung Thanh Nguyen,1b Gary Wilson standards, the clients of software libraries often need to make correspond- ing changes to correctly use

  1. Development of the TIGRE This describes the TIGRE method for combinator graph reduction.

    E-Print Network [OSTI]

    Koopman, Philip

    been previously implemented for the G-Ma- chine graph reduction implementation on a VAX (Peyton Jones 1987). In VAX assembly language, unwinding a node while traversing the stack requires four instructions, on average, processing nodes for stack unwinding costs: (4 * 1.38) + 7 = 12.52 VAX instructions per

  2. Planar Hop Spanners for Unit Disk Graphs Nicolas Catusse, Victor Chepoi, and Yann Vax`es

    E-Print Network [OSTI]

    Chepoi, Victor

    Planar Hop Spanners for Unit Disk Graphs Nicolas Catusse, Victor Chepoi, and Yann Vax`es Marseille Cedex 9, France {nicolas.catusse,victor.chepoi,yann.vaxes}@lif.univ-mrs.fr Abstract. The simplest;2 Nicolas Catusse, Victor Chepoi, and Yann Vax`es factors (see [9], for instance), the problem

  3. Organization of cortical areas in central and peripheral visual fields as revealed by graph theory analysis

    E-Print Network [OSTI]

    Jouve, Bertrand

    1 Organization of cortical areas in central and peripheral visual fields as revealed by graph theory analysis Kenneth Knoblauch, Bertrand Jouve, Arnaud Falchier, Laetitia Cirilli and Henry Kennedy patterns of connections between visual areas so as to determine the prin­ ciples of cortical organization

  4. Muller's ratchet in random graphs and scale-free networks Paulo R. A. Campos,1,

    E-Print Network [OSTI]

    Dionisio, Francisco

    Muller's ratchet in random graphs and scale-free networks Paulo R. A. Campos,1, * Jaime Combadão,2 manuscript received 1 September 2006; published 4 October 2006 Muller's ratchet is an evolutionary process study the speed of Muller's ratchet in a population subdivided into many small subpopulations connected

  5. Fully Distributed Trust Model based on Trust Graph for Mobile Ad hoc Networks

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    University of Technology, France. bouabdal@hds.utc.fr Abstract A mobile ad hoc network (MANET) is a wireless pre-existing in- frastructure; all networking operations (routing, mobility management, and so onFully Distributed Trust Model based on Trust Graph for Mobile Ad hoc Networks Mawloud Omar, Yacine

  6. Enumerating the edge-colourings of a regular graph Stephane Bessy and Frederic Havet

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Enumerating the edge-colourings of a regular graph St´ephane Bessy and Fr´ed´eric Havet Assistant and Combinatorics Deparment of Applied Mathematics, National Sun Yat-sen University, Kaohsiung, Taiwan. S. Bessy. Bessy and F.Havet () Enumerating the edge-colourings WGTC, Kaohsiung, 2012 2 / 41 lirmm-00811571,version

  7. DNA fragment assembly: an application of graph theory in molecular biology

    E-Print Network [OSTI]

    Willems, Wolfgang

    DNA fragment assembly: an application of graph theory in molecular biology Martin Mascher Leibniz Technology Since the central importance of the DNA in storing biological informa- tion had been recognised limitations permit scientists only to obtain contigu- ous DNA fragments whose lengths range from a few dozen

  8. A Discrete Chain Graph Model for 3d+t Cell Tracking with High

    E-Print Network [OSTI]

    Heermann, Dieter W.

    the exact MAP solution by integer linear programming (ILP), and­ when comparing to the gold standard by assignment is well suited for tracking a varying number of divisible cells, but suffers from false positive detections. We reformulate tracking by assignment as a chain graph­a mixed directed- undirected probabilistic

  9. Limits on the network sensitivity function for homogeneous multi-agent systems on a graph

    E-Print Network [OSTI]

    Murray, Richard M.

    in feedback control of interconnected multi- agent systems, focused on the network sensitivity functions. We linear dynamics and we model the interconnection topology as a graph, in which the single agents], edge agreement [5], [6], linear quadratic regulator [7], decomposition and linear matrix inequalities

  10. 1 Introduction 1 1.1 Graphs, digraphs, and homomorphisms 1

    E-Print Network [OSTI]

    Hell, Pavol

    CONTENTS 1 Introduction 1 1.1 Graphs, digraphs, and homomorphisms 1 1.2 Homomorphisms preserve adjacency 3 1.3 Homomorphisms generalize colourings 6 1.4 The existence of homomorphisms 10 1.5 Homomorphisms generalize isomorphisms 16 1.6 Homomorphic equivalence 18 1.7 The composition of homomorphisms 20

  11. Social Networks 29 (2007) 231248 Advances in exponential random graph (p*

    E-Print Network [OSTI]

    Fienberg, Stephen E.

    2007-01-01T23:59:59.000Z

    Social Networks 29 (2007) 231­248 Advances in exponential random graph (p* ) models applied to a large social network Steven M. Goodreau University of Washington, Department of Anthropology and Center ability to conduct inference on dependence in large social networks [Snijders, T.A.B., 2002. Markov Chain

  12. Social Networks 29 (2007) 169172 Advances in exponential random graph (p*

    E-Print Network [OSTI]

    Fienberg, Stephen E.

    2007-01-01T23:59:59.000Z

    Social Networks 29 (2007) 169­172 Editorial Advances in exponential random graph (p* ) models Statistical approaches to social networks have a rather long history. Few now recall that Moreno and Jennings networks. But to specify a successful statistical model for a social network has been a more difficult

  13. Algebraic Higher-Order Nets: Graphs and Petri Nets as Tokens

    E-Print Network [OSTI]

    Mossakowski, Till - Deutschen Forschungszentrum für Künstliche Intelligenz & Fachbereich 3

    Algebraic Higher-Order Nets: Graphs and Petri Nets as Tokens Kathrin Hoffmann1 and Till Mossakowski 2 BISS, Department of Computer Science University of Bremen Abstract. Petri nets and Algebraic High-Level Nets are well-known to model parallel and concurrent systems. In this paper, we introduce the concept

  14. Algebraic HigherOrder Nets: Graphs and Petri Nets as Tokens

    E-Print Network [OSTI]

    Mossakowski, Till - Deutschen Forschungszentrum für Künstliche Intelligenz & Fachbereich 3

    Algebraic Higher­Order Nets: Graphs and Petri Nets as Tokens Kathrin Ho#mann 1 and Till Mossakowski 2 BISS, Department of Computer Science University of Bremen Abstract. Petri nets and Algebraic High­Level Nets are well­known to model parallel and concurrent systems. In this paper, we introduce the concept

  15. On the edge-connectivity of Cartesian product graphs Sandi Klavzar

    E-Print Network [OSTI]

    Klavzar, Sandi

    , then either S is induced by a minimum edge cut of a factor, or S is a set of edges incident to a vertex of G H is given and the structure of minimum edge cuts is described. It is also proved that the connectivity product of graphs; edge-connectivity; minimum edge cuts; AMS subject classification (2000): 05C40 1

  16. Distributed Detection in Sensor Networks: Connectivity Graph and Small World Networks

    E-Print Network [OSTI]

    Moura, José

    Distributed Detection in Sensor Networks: Connectivity Graph and Small World Networks Saeed A study distributed detection in a sensor network where the sensors cooperate by exchanging information distributed decision making algorithms in the network. This is a difficult problem since it corresponds

  17. The critical group of a graph Texas State U., San Marcos, March 21th, 2014.

    E-Print Network [OSTI]

    Sin, Peter

    -firing game (Björner-Lovasz-Shor, Gabrielov, Biggs); #12;This talk is about the critical group, a finite-Tang-Wiesenfeld, Dhar); its combinatorial variant: the Chip-firing game (Björner-Lovasz-Shor, Gabrielov, Biggs-Lovasz-Shor, Gabrielov, Biggs); in arithmetic geometry: Picard group, graph Jacobian (Lorenzini). We'll consider

  18. The critical group of a graph Millican Colloquium, UNT, March 24th, 2014.

    E-Print Network [OSTI]

    Sin, Peter

    -firing game (Björner-Lovasz-Shor, Gabrielov, Biggs); #12;This talk is about the critical group, a finite-Tang-Wiesenfeld, Dhar); its combinatorial variant: the Chip-firing game (Björner-Lovasz-Shor, Gabrielov, Biggs-Lovasz-Shor, Gabrielov, Biggs); in arithmetic geometry: Picard group, graph Jacobian (Lorenzini). We'll consider

  19. Interactive Graph Cut Based Segmentation With Shape Priors Daniel Freedman and Tao Zhang

    E-Print Network [OSTI]

    Interactive Graph Cut Based Segmentation With Shape Priors Daniel Freedman and Tao Zhang Computer segmentation can be very chal- lenging, a small amount of user input can often resolve ambiguous decisions can be very chal- lenging, a small amount of user input can often resolve am- biguous decisions

  20. Bond Graph Model of a Vertical U-Tube Steam Condenser Coupled with a Heat Exchanger

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    turbines, distillation industries using water as a solvent, etc. System-level modeling of steam condensersBond Graph Model of a Vertical U-Tube Steam Condenser Coupled with a Heat Exchanger K. Medjaher1+ A A simulation model for a vertical U-tube steam condenser in which the condensate is stored at the bottom well

  1. A functional central limit theorem for interacting particle systems on transitive graphs

    E-Print Network [OSTI]

    Paul Doukhan; Gabriel Lang; Sana Louhichi; Bernard Ycart

    2007-04-12T23:59:59.000Z

    A finite range interacting particle system on a transitive graph is considered. Assuming that the dynamics and the initial measure are invariant, the normalized empirical distribution process converges in distribution to a centered diffusion process. As an application, a central limit theorem for certain hitting times, interpreted as failure times of a coherent system in reliability, is derived.

  2. And-Invert-Graphs (AIGs) for Equivalence Verification, SAT Modulo Theory (SMT) Solvers, and the Motivation

    E-Print Network [OSTI]

    Kalla, Priyank

    And-Invert-Graphs (AIGs) for Equivalence Verification, SAT Modulo Theory (SMT) Solvers-learning Key idea: identify internal structural equivalences P. Kalla (Univ. of Utah) AIGs, SMT, Algebra of transformations Verification = reverse these transformations? Kind of... P. Kalla (Univ. of Utah) AIGs, SMT

  3. The AME2003 atomic mass evaluation (II). Tables, graphs and references

    E-Print Network [OSTI]

    Boyer, Edmond

    with the binding energy per nucleon, the beta-decay energy and the full atomic mass in mass units. * This work has&UPS, B^atiment 108, F-91405 Orsay Campus, France b National Institute of Nuclear Physics and High-Energy, a table of separation energies and reaction energies, and finally, a series of graphs of separation

  4. VIDEO SUMMARIZATION BY SPATIAL-TEMPORAL GRAPH OPTIMIZATION Shi Lu, Michael R. Lyu, Irwin King

    E-Print Network [OSTI]

    King, Kuo Chin Irwin

    VIDEO SUMMARIZATION BY SPATIAL-TEMPORAL GRAPH OPTIMIZATION Shi Lu, Michael R. Lyu, Irwin King SAR {slu, lyu, king}@cse.cuhk.edu.hk ABSTRACT In this paper we present a novel approach for video sum-temporal content cov- erage and visual coherence of the video summary. The ap- proach has three stages. First

  5. Absolutely continuous spectrum implies ballistic transport for quantum particles in a random potential on tree graphs

    SciTech Connect (OSTI)

    Aizenman, Michael [Departments of Physics and Mathematics, Princeton University, Princeton, New Jersey 08544 (United States); Warzel, Simone [Zentrum Mathematik, TU Munich, Boltzmannstr. 3, 85747 Garching (Germany)

    2012-09-15T23:59:59.000Z

    We discuss the dynamical implications of the recent proof that for a quantum particle in a random potential on a regular tree graph absolutely continuous (ac) spectrum occurs non-perturbatively through rare fluctuation-enabled resonances. The main result is spelled in the title.

  6. .1October 8, 2005Copyright Albert R. Meyer, 2005. All rights reserved. Planar Graphs

    E-Print Network [OSTI]

    Goldwasser, Shafi

    .1October 8, 2005Copyright © Albert R. Meyer, 2005. All rights reserved. Drawing Planar Graphs Mathematics for Computer Science MIT 6.042J/18.062J #12;.2October 8, 2005Copyright © Albert R. Meyer, 2005 edges crossing. #12;.3October 8, 2005Copyright © Albert R. Meyer, 2005. All rights reserved. Planar

  7. The stackelberg minimum spanning tree game on planar and bounded-treewidth graphs

    E-Print Network [OSTI]

    Cardinal, Jean

    The Stackelberg Minimum Spanning Tree Game is a two-level combinatorial pricing problem introduced at WADS’07. The game is played on a graph, whose edges are colored either red or blue, and where the red edges have a given ...

  8. Scheduling Parallel Task Graphs on (Almost) Homogeneous Multi-cluster Platforms

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Scheduling Parallel Task Graphs on (Almost) Homogeneous Multi-cluster Platforms Pierre these applications efficiently on parallel platforms has been a long-standing challenge. In the case of a single homogeneous platform, such as a cluster, results have been obtained both in theory, i.e., guaranteed

  9. Critical Path and Area Based Scheduling of Parallel Task Graphs on Heterogeneous Platforms

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Critical Path and Area Based Scheduling of Parallel Task Graphs on Heterogeneous Platforms Tchimou research has been done in the context of single homogeneous clus- ters, heterogeneous platforms have become) a novel "virtual" cluster methodology for handling platform het- erogeneity; (ii) a novel task placement

  10. A Distributed Polylogarithmic Time Algorithm for Self-Stabilizing Skip Graphs

    E-Print Network [OSTI]

    Richa, Andrea Werneck

    A Distributed Polylogarithmic Time Algorithm for Self-Stabilizing Skip Graphs Riko Jacob Dept. Computer Science Technische Universität München D-85748 Garching bei München, Germany jacob or commercial advantage and that copies bear this notice and the full citation on the first page. To copy

  11. SUGI 15, April, 1990 SAS/GRAPH SOFTWARE MEETS THE LOGO TURTLE

    E-Print Network [OSTI]

    Friendly, Michael

    SUGI 15, April, 1990 SAS/GRAPH® SOFTWARE MEETS THE LOGO TURTLE Michael Friendly, York University Abstract What is Logo? This talk describes a set of SAS macros which provide the ability to Logo of the Logo language, rather setting. Part of its appeal is an extremely simple yet flexible than absolute X

  12. A NOVEL FRAMEWORK FOR ACCURATE LUNG SEGMENTATION USING GRAPH CUTS Asem M. Ali1

    E-Print Network [OSTI]

    Louisville, University of

    A NOVEL FRAMEWORK FOR ACCURATE LUNG SEGMENTATION USING GRAPH CUTS Asem M. Ali1 Ayman S. El-Baz 2 Bioengineering Department, University of Louisville ABSTRACT The closeness of the gray levels between lung tissues and the chest tissues makes lung segmentation based only on image signals dif- ficult. This work

  13. Automatic Lung Segmentation of Volumetric Low-Dose CT Scans Using Graph Cuts

    E-Print Network [OSTI]

    Farag, Aly A.

    Automatic Lung Segmentation of Volumetric Low-Dose CT Scans Using Graph Cuts Asem M. Ali and Aly A for unsupervised segmentation of the lung region from low dose computed tomography (LDCT) images. We follow distribution model. To better spec- ify region borders between lung and chest, each empirical distribution

  14. Kronk, Hudson V., Associate Professor, PhD, 1964, Michigan State University: Graph theory.

    E-Print Network [OSTI]

    Suzuki, Masatsugu

    227 Kronk, Hudson V., Associate Professor, PhD, 1964, Michigan State University: Graph theory. (1964) Lercher, Bruce L., Associate Professor Emeritus, PhD, 1963, Pennsylvania State University: Mathematical logic. (1962) McAuley, Louis F., Professor, PhD, 1954, University of North Carolina: Topology

  15. Lower bounds on the obstacle number of graphs Padmini Mukkamala1, Janos Pach2, and Domotor Palvolgyi3

    E-Print Network [OSTI]

    Pach, János

    Lower bounds on the obstacle number of graphs Padmini Mukkamala1, J´anos Pach2, and D¨om¨ot¨or P are extensively studied and used in computational geometry, robot motion planning, computer vision, sensor

  16. Multi-Agent Deterministic Graph Mapping via Robot Rendezvous Chaohui Gong, Stephen Tully, George Kantor, and Howie Choset

    E-Print Network [OSTI]

    Choset, Howie

    Multi-Agent Deterministic Graph Mapping via Robot Rendezvous Chaohui Gong, Stephen Tully, George at Carnegie Mellon University, Pittsburgh, PA 15213, USA. C. Gong, G. Kantor, and H. Choset

  17. On covering planar graphs with a fixed number of balls Victor Chepoi, Bertrand Estellon, Yann Vax`es

    E-Print Network [OSTI]

    Chepoi, Victor

    On covering planar graphs with a fixed number of balls Victor Chepoi, Bertrand Estellon, Yann Vax`es´editerran´ee, F-13288 Marseille Cedex 9, France, {chepoi,estellon,vaxes}@lif.univ-mrs.fr Abstract. In this note

  18. The relationship between graphing calculator use and the development of classroom norms in an exemplay teacher's college algebra course

    E-Print Network [OSTI]

    Gerren, Sally Sue

    2008-10-10T23:59:59.000Z

    to explore the question: What happens when an exemplary teacher uses graphing calculators in a college algebra class? The purposively selected participants were the teacher and eleven students of a Texas community college algebra course. All 29 classes...

  19. Discrete Mathematics and Theoretical Computer Science DMTCS vol. 12:3, 2010, 6374 Covering codes in Sierpinski graphs

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Discrete Mathematics and Theoretical Computer Science DMTCS vol. 12:3, 2010, 63­74 Covering codesth May 2010. For a graph G and integers a and b, an (a, b)-code of G is a set C of vertices. In this paper we classify integers a and b for which there exist (a, b)-codes in Sierpi´nski graphs. Keywords

  20. Exact scattering matrix of graphs in magnetic field and quantum noise

    SciTech Connect (OSTI)

    Caudrelier, Vincent, E-mail: v.caudrelier@city.ac.uk [Department of Mathematical Science, City University London, Northampton Square, London EC1V 0HB (United Kingdom); Mintchev, Mihail, E-mail: mintchev@df.unipi.it [Istituto Nazionale di Fisica Nucleare and Dipartimento di Fisica dell’Università di Pisa, Largo Pontecorvo 3, 56127 Pisa (Italy); Ragoucy, Eric, E-mail: eric.ragoucy@lapth.cnrs.fr [LAPTh, Laboratoire d’Annecy-le-Vieux de Physique Théorique, CNRS, Université de Savoie, BP 110, 74941 Annecy-le-Vieux Cedex (France)

    2014-08-15T23:59:59.000Z

    We consider arbitrary quantum wire networks modelled by finite, noncompact, connected quantum graphs in the presence of an external magnetic field. We find a general formula for the total scattering matrix of the network in terms of its local scattering properties and its metric structure. This is applied to a quantum ring with N external edges. Connecting the external edges of the ring to heat reservoirs, we study the quantum transport on the graph in ambient magnetic field. We consider two types of dynamics on the ring: the free Schrödinger and the free massless Dirac equations. For each case, a detailed study of the thermal noise is performed analytically. Interestingly enough, in presence of a magnetic field, the standard linear Johnson-Nyquist law for the low temperature behaviour of the thermal noise becomes nonlinear. The precise regime of validity of this effect is discussed and a typical signature of the underlying dynamics is observed.

  1. Instability of Bose-Einstein condensation on quantum graphs under repulsive perturbations

    E-Print Network [OSTI]

    Jens Bolte; Joachim Kerner

    2014-11-26T23:59:59.000Z

    In this Note we investigate Bose-Einstein condensation in interacting quantum many-particle systems on graphs. We extend previous results obtained for particles on an interval and show that even arbitrarily small repulsive two-particle interactions destroy a condensate in the non-interacting Bose gas. Our results also cover singular two-particle interactions, such as the well-known Lieb-Lininger model, in the thermodynamic limit.

  2. Dynamic Motion Graphs Bjrn Krger1, Arno Zinke2, Andreas Weber1

    E-Print Network [OSTI]

    Bonn, Universität

    Dynamic Motion Graphs Björn Krüger1, Arno Zinke2, Andreas Weber1 1Institute of Computer Science II, University of Bonn 2GfaR mbH, Bonn e-mail: {kruegerb, zinke, weber}@cs.uni-bonn.de Introduction Method result. [KTWZ10] KR�GER, B., TAUTGES, J., WEBER, A., AND ZINKE, A. Fast local and global similarity

  3. ISOPERIMETRIC CONSTANT OF A k-REGULAR GRAPH (A NOTE ON A THEOREM OF

    E-Print Network [OSTI]

    Smirnova-Nagnibeda, Tatiana

    ISOPERIMETRIC CONSTANT OF A k-REGULAR GRAPH (A NOTE ON A THEOREM OF BIGGS, MOHAR, AND SHAWE.2 in the paper [BMS] of Biggs, Mohar, and Shawe-Taylor we have instead of (1) and (2): i #21; 4(1 #26;) , #26 that #26; #20; q 1 i 2 k 2 . References BMS. N. Biggs, B. Mohar, J. Shawe-Taylor, The spectral radius of in

  4. Efficient Graph Based Assembly of Short-Read Sequences on Hybrid Core Architecture

    SciTech Connect (OSTI)

    Sczyrba, Alex; Pratap, Abhishek; Canon, Shane; Han, James; Copeland, Alex; Wang, Zhong; Brewer, Tony; Soper, David; D'Jamoos, Mike; Collins, Kirby; Vacek, George

    2011-03-22T23:59:59.000Z

    Advanced architectures can deliver dramatically increased throughput for genomics and proteomics applications, reducing time-to-completion in some cases from days to minutes. One such architecture, hybrid-core computing, marries a traditional x86 environment with a reconfigurable coprocessor, based on field programmable gate array (FPGA) technology. In addition to higher throughput, increased performance can fundamentally improve research quality by allowing more accurate, previously impractical approaches. We will discuss the approach used by Convey?s de Bruijn graph constructor for short-read, de-novo assembly. Bioinformatics applications that have random access patterns to large memory spaces, such as graph-based algorithms, experience memory performance limitations on cache-based x86 servers. Convey?s highly parallel memory subsystem allows application-specific logic to simultaneously access 8192 individual words in memory, significantly increasing effective memory bandwidth over cache-based memory systems. Many algorithms, such as Velvet and other de Bruijn graph based, short-read, de-novo assemblers, can greatly benefit from this type of memory architecture. Furthermore, small data type operations (four nucleotides can be represented in two bits) make more efficient use of logic gates than the data types dictated by conventional programming models.JGI is comparing the performance of Convey?s graph constructor and Velvet on both synthetic and real data. We will present preliminary results on memory usage and run time metrics for various data sets with different sizes, from small microbial and fungal genomes to very large cow rumen metagenome. For genomes with references we will also present assembly quality comparisons between the two assemblers.

  5. Experimental investigation of Wigner's reaction matrix for irregular graphs with absorption

    E-Print Network [OSTI]

    Oleh Hul; Oleg Tymoshchuk; Szymon Bauch; Peter M. Koch; Leszek Sirko

    2009-03-12T23:59:59.000Z

    We use tetrahedral microwave networks consisting of coaxial cables and attenuators connected by T-joints to make an experimental study of Wigner's reaction K matrix for irregular graphs in the presence of absorption. From measurements of the scattering matrix S for each realization of the microwave network we obtain distributions of the imaginary and real parts of K. Our experimental results are in good agreement with theoretical predictions.

  6. Scaling Graph Community Detection on the Tilera Many-core Architecture

    SciTech Connect (OSTI)

    Chavarría-Miranda, Daniel; Halappanavar, Mahantesh; Kalyanaraman, Anantharaman

    2014-12-01T23:59:59.000Z

    In an era when power constraints and data movement are proving to be significant barriers for the application of high-end computing, the Tilera many-core architecture offers a low-power platform exhibiting many important characteristics of future systems, including a large number of simple cores, a sophisticated network-on-chip, and fine-grained control over memory and caching policies. While this emerging architecture has been previously studied for structured compute-intensive kernels, benchmarking the platform for data-bound, irregular applications present significant challenges that have remained unexplored. Community detection is an advanced prototypical graph-theoretic operation with applications in numerous scientific domains including life sciences, cyber security, and power systems. In this work, we explore multiple design strategies toward developing a scalable tool for community detection on the Tilera platform. Using several memory layout and work scheduling techniques we demonstrate speedups of up to 46x on 36 cores of the Tilera TileGX36 platform over the best serial implementation, and also show results that have comparable quality and performance to mainstream x86 platforms. To the best of our knowledge this is the first work addressing graph algorithms on the Tilera platform. This study demonstrates that through careful design space exploration, low-power many-core platforms like Tilera can be effectively exploited for graph algorithms that that embody all the essential characteristics of an irregular application.

  7. Sampling graphs with a prescribed joint degree distribution using Markov Chains.

    SciTech Connect (OSTI)

    Pinar, Ali; Stanton, Isabelle (UC Berkeley)

    2010-10-01T23:59:59.000Z

    One of the most influential results in network analysis is that many natural networks exhibit a power-law or log-normal degree distribution. This has inspired numerous generative models that match this property. However, more recent work has shown that while these generative models do have the right degree distribution, they are not good models for real life networks due to their differences on other important metrics like conductance. We believe this is, in part, because many of these real-world networks have very different joint degree distributions, i.e. the probability that a randomly selected edge will be between nodes of degree k and l. Assortativity is a sufficient statistic of the joint degree distribution, and it has been previously noted that social networks tend to be assortative, while biological and technological networks tend to be disassortative. We suggest that the joint degree distribution of graphs is an interesting avenue of study for further research into network structure. We provide a simple greedy algorithm for constructing simple graphs from a given joint degree distribution, and a Monte Carlo Markov Chain method for sampling them. We also show that the state space of simple graphs with a fixed degree distribution is connected via endpoint switches. We empirically evaluate the mixing time of this Markov Chain by using experiments based on the autocorrelation of each edge.

  8. Compact Graph Representations and Parallel Connectivity Algorithms for Massive Dynamic Network Analysis

    SciTech Connect (OSTI)

    Madduri, Kamesh; Bader, David A.

    2009-02-15T23:59:59.000Z

    Graph-theoretic abstractions are extensively used to analyze massive data sets. Temporal data streams from socioeconomic interactions, social networking web sites, communication traffic, and scientific computing can be intuitively modeled as graphs. We present the first study of novel high-performance combinatorial techniques for analyzing large-scale information networks, encapsulating dynamic interaction data in the order of billions of entities. We present new data structures to represent dynamic interaction networks, and discuss algorithms for processing parallel insertions and deletions of edges in small-world networks. With these new approaches, we achieve an average performance rate of 25 million structural updates per second and a parallel speedup of nearly28 on a 64-way Sun UltraSPARC T2 multicore processor, for insertions and deletions to a small-world network of 33.5 million vertices and 268 million edges. We also design parallel implementations of fundamental dynamic graph kernels related to connectivity and centrality queries. Our implementations are freely distributed as part of the open-source SNAP (Small-world Network Analysis and Partitioning) complex network analysis framework.

  9. Positivity of the virial coefficients in lattice dimer models and upper bounds on the number of matchings on graphs

    E-Print Network [OSTI]

    P. Butera; P. Federbush; M. Pernici

    2015-02-24T23:59:59.000Z

    Using a relation between the virial expansion coefficients of the pressure and the entropy expansion coefficients in the case of the monomer-dimer model on infinite regular lattices, we have shown that, on hypercubic lattices of any dimension, the virial coefficients are positive through the 20th order. We have observed that all virial coefficients so far known for this system are positive also on infinite regular lattices with different structure. We are thus led to conjecture that the virial expansion coefficients $m_k $ are always positive. These considerations can be extended to the study of related bounds on finite graphs generalizing the infinite regular lattices, namely the finite grids and the regular biconnected graphs. The validity of the bounds $\\Delta^k {\\rm ln}(i! N(i)) \\le 0$ for $k \\ge 2$, where $N(i)$ is the number of configurations of $i$ dimers on the graph and $\\Delta$ is the forward difference operator, is shown to correspond to the positivity of the virial coefficients. Our tests on many finite lattice graphs indicate that on large lattices these bounds are satisfied, giving support to the conjecture on the positivity of the virial coefficients. An exhaustive survey of some classes of regular biconnected graphs with a not too large number $v$ of vertices shows only few violations of these bounds. We conjecture that the frequency of the violations vanishes as $v \\to \\infty$. We find rigorous upper bounds on $N(i)$ valid for arbitrary graphs and for regular graphs. The similarity between the Heilman-Lieb inequality and the one conjectured above suggests that one study the stricter inequality $m_k \\ge \\frac{1}{2k}$ for the virial coefficients, which is valid for all the known coefficients of the infinite regular lattice models.

  10. On the Irreps of the N-Extended Supersymmetric Quantum Mechanics and Their Fusion Graphs

    E-Print Network [OSTI]

    Francesco Toppan

    2006-12-27T23:59:59.000Z

    In this talk we review the classification of the irreducible representations of the algebra of the N-extended one-dimensional supersymmetric quantum mechanics presented in hep-th/0511274. We answer some issues raised in hep-th/0611060, proving the agreement of the results here contained with those in hep-th/0511274. We further show that the fusion algebra of the 1D N-extended supersymmetric vacua introduced in hep-th/0511274 admits a graphical presentation. The N=2 graphs are here explicitly presented for the first time.

  11. Distance-regular graphs of $q$-Racah type and the $q$-tetrahedron algebra

    E-Print Network [OSTI]

    Ito, Tatsuro

    2007-01-01T23:59:59.000Z

    In this paper we discuss a relationship between the following two algebras: (i) the subconstituent algebra $T$ of a distance-regular graph that has $q$-Racah type; (ii) the $q$-tetrahedron algebra $\\boxtimes_q$ which is a $q$-deformation of the three-point $sl_2$ loop algebra. Assuming that every irreducible $T$-module is thin, we display an algebra homomorphism from $\\boxtimes_q$ into $T$ and show that $T$ is generated by the image together with the center $Z(T)$.

  12. MadDM v.1.0: Computation of Dark Matter Relic Abundance Using MadGraph5

    E-Print Network [OSTI]

    Mihailo Backovic; Kyoungchul Kong; Mathew McCaskey

    2014-04-24T23:59:59.000Z

    We present MadDM v.1.0, a numerical tool to compute dark matter relic abundance in a generic model. The code is based on the existing MadGraph 5 architecture and as such is easily integrable into any MadGraph collider study. A simple Python interface offers a level of user-friendliness characteristic of MadGraph 5 without sacrificing functionality. MadDM is able to calculate the dark matter relic abundance in models which include a multi-component dark sector, resonance annihilation channels and co-annihilations. We validate the code in a wide range of dark matter models by comparing the relic density results from MadDM to the existing tools and literature.

  13. On a correspondence principle between discrete differential forms, graph structure and multi-vector calculus on symmetric lattices

    E-Print Network [OSTI]

    Nelson Faustino; Uwe Kaehler

    2015-05-31T23:59:59.000Z

    Based on \\cite{DH94}, we introduce a bijective correspondence between first order differential calculi and the graph structure of the symmetric lattice that allows one to encode completely the interconnection structure of the graph in the exterior derivative. As a result, we obtain the Grassmannian character of the lattice as well as the mutual commutativity between basic vector-fields on the tangent space. This in turn gives several similarities between the Clifford setting and the algebra of endomorphisms endowed by the graph structure, such as the hermitian structure of the lattice as well as the Clifford-like algebra of operators acting on the lattice. This naturally leads to a discrete version of Clifford Analysis.

  14. Experimental and numerical investigation of the reflection coefficient and the distributions of Wigner's reaction matrix for irregular graphs with absorption

    E-Print Network [OSTI]

    Michal Lawniczak; Oleh Hul; Szymon Bauch; Petr Seba; Leszek Sirko

    2009-03-18T23:59:59.000Z

    We present the results of experimental and numerical study of the distribution of the reflection coefficient P(R) and the distributions of the imaginary P(v) and the real P(u) parts of the Wigner's reaction K matrix for irregular fully connected hexagon networks (graphs) in the presence of strong absorption. In the experiment we used microwave networks, which were built of coaxial cables and attenuators connected by joints. In the numerical calculations experimental networks were described by quantum fully connected hexagon graphs. The presence of absorption introduced by attenuators was modelled by optical potentials. The distribution of the reflection coefficient P(R) and the distributions of the reaction K matrix were obtained from the measurements and numerical calculations of the scattering matrix S of the networks and graphs, respectively. We show that the experimental and numerical results are in good agreement with the exact analytic ones obtained within the framework of random matrix theory (RMT).

  15. A preliminary version appeared in Advances in Cryptology --Asiacrypt'02. This is a revised version. The Provable Security of GraphBased OneTime Signatures and

    E-Print Network [OSTI]

    Hevia, Alejandro

    A preliminary version appeared in Advances in Cryptology -- Asiacrypt'02. This is a revised version based on ``graphs of one­way functions''. Bleichen­ bacher and Maurer thoroughly analyze graph based . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 The GBOTS construction 7 4 The Reduction 8 4.1 Inverting H

  16. A preliminary version appeared in Advances in Cryptology Asiacrypt'02. This is a revised version. The Provable Security of Graph-Based One-Time Signatures and

    E-Print Network [OSTI]

    Hevia, Alejandro

    A preliminary version appeared in Advances in Cryptology ­ Asiacrypt'02. This is a revised version based on "graphs of one-way functions". Bleichen- bacher and Maurer thoroughly analyze graph based . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 The GBOTS construction 7 4 The Reduction 8 4.1 Inverting H

  17. Mathematical Proofs of Two Conjectures: The Four Color Problem and The Uniquely 4-colorable Planar Graph

    E-Print Network [OSTI]

    Jin Xu

    2012-01-18T23:59:59.000Z

    The famous four color theorem states that for all planar graphs, every vertex can be assigned one of 4 colors such that no two adjacent vertices receive the same color. Since Francis Guthrie first conjectured it in 1852, it is until 1976 with electronic computer that Appel and Haken first gave a proof by finding and verifying 1936 reducible unavoidable sets, and a simplified proof of Robertson, Sanders, Seymour and Thomas in 1997 only involved 633 reducible unavoidable sets, both proofs could not be realized effectively by hand. Until now, finding the reducible unavoidable sets remains the only successful method to use, which came from Kempe's first "proof" of the four color problem in 1879. An alternative method only involving 4 reducible unavoidable sets for proving the four color theorem is used in this paper, which takes form of mathematical proof rather than a computer-assisted proof and proves both the four color conjecture and the uniquely 4-colorable planar graph conjecture by mathematical method.

  18. Finding Statistics & Data at Queen's Sept/08 STATISTICS Facts & figures in tables, charts, time series, graphs, etc.

    E-Print Network [OSTI]

    Abolmaesumi, Purang

    Finding Statistics & Data at Queen's Sept/08 STATISTICS Facts & figures in tables, charts, time series, graphs, etc. 1. Statistics Canada www.statcan.ca English use the search box... REMEMBER: Don't Pay Contact madgic@queensu.ca to get statistics for free if faced with a fee! 2. Social

  19. DISTRIBUTED KALMAN FILTERS IN SENSOR NETWORKS: BIPARTITE FUSION GRAPHS Usman A. Khan and Jose M. F. Moura

    E-Print Network [OSTI]

    Moura, José

    DISTRIBUTED KALMAN FILTERS IN SENSOR NETWORKS: BIPARTITE FUSION GRAPHS Usman A. Khan and Jos´e M. F {ukhan, moura}@ece.cmu.edu ABSTRACT We study the distributed Kalman filter in sensor networks where into reduced coupled sensor-based models. We implement local Kalman filters on these reduced models

  20. GeoTriples: a Tool for Publishing Geospatial Data as RDF Graphs Using R2RML Mappings

    E-Print Network [OSTI]

    Koubarakis, Manolis

    GeoTriples: a Tool for Publishing Geospatial Data as RDF Graphs Using R2RML Mappings Kostis the tool GeoTriples that allows the transformation of Earth Observation data and geospatial data into RDF of geospatial data. GeoTriples is a semi- automated tool that transforms geospatial information into RDF follow

  1. The Stata Journal, 2002, 3, pp 316-327 The Clustergram: A graph for visualizing hierarchical and

    E-Print Network [OSTI]

    Schonlau, Matt

    . This graph is useful in exploratory analysis for non-hierarchical clustering algorithms like k-means linkage methods is of order O(n2 ), whereas the most popular non-hierarchical cluster algorithm, k-means ([R] cluster kmeans, MacQueen, 1967), is only of the order O(kn) where k is the number of clusters

  2. A SPATIAL WEB GRAPH MODEL WITH LOCAL INFLUENCE W. AIELLO, A. BONATO, C. COOPER, J. JANSSEN, AND P. PRALAT

    E-Print Network [OSTI]

    Janssen, Jeannette C.M.

    technique, web pages are often represented as vectors in a word-document space. Using Latent SematicA SPATIAL WEB GRAPH MODEL WITH LOCAL INFLUENCE REGIONS W. AIELLO, A. BONATO, C. COOPER, J. JANSSEN in [2, ) depending on the parameters, and with concentration for a wide range of in-degree values. We

  3. To be published in Computers & Graphics, vol. 28, no. 6, 2004. Point Cloud Surfaces using Geometric Proximity Graphs

    E-Print Network [OSTI]

    Behnke, Sven

    Proximity Graphs Jan Klein a and Gabriel Zachmann b aHeinz Nixdorf Institute and Institute of Computer@cs.uni-bonn.de (Gabriel Zachmann). In this paper, we present a new definition of a surface over a given point cloud

  4. To be published in Computers & Graphics, vol. 28, no. 6, 2004. Point Cloud Surfaces using Geometric Proximity Graphs

    E-Print Network [OSTI]

    Zachmann, Gabriel

    Proximity Graphs Jan Klein a and Gabriel Zachmann b a Heinz Nixdorf Institute and Institute of Computer@cs.uni­bonn.de (Gabriel Zachmann). In this paper, we present a new definition of a surface over a given point cloud

  5. EDGAR: Explicit Demand Graph I have demonstrated how slivers and synchronized lazy aggregates can be realized using

    E-Print Network [OSTI]

    Turbak, Franklyn

    Chapter 8 EDGAR: Explicit Demand Graph Reduction I have demonstrated how slivers and synchronized (Edgar), a frame­ work that I have developed for describing how computations unfold over time. Whereas many semantic frameworks focus on the value produced by a computation, Edgar is de­ signed to emphasize

  6. TauDecay: a library to simulate polarized tau decays via FeynRules and MadGraph5

    E-Print Network [OSTI]

    Kaoru Hagiwara; Tong Li; Kentarou Mawatari; Junya Nakamura

    2014-12-15T23:59:59.000Z

    TauDecay is a library of helicity amplitudes to simulate polarized tau decays, constructed in the FeynRules and MadGraph5 framework. Together with the leptonic mode, the decay library includes the main hadronic modes, \\tau \\to \

  7. Under consideration for publication in Theory and Practice of Logic Programming 1 Causal Graph Justifications of Logic Programs

    E-Print Network [OSTI]

    Cabalar, Pedro

    . An This research was partially supported by Spanish MEC project TIN2009-14562-C05-04, Xunta program INCITE 2011Under consideration for publication in Theory and Practice of Logic Programming 1 Causal Graph Justifications of Logic Programs Pedro Cabalar, Jorge Fandinno Department of Computer Science University

  8. Understanding resonance graphs using Easy Java Simulations (EJS) and why we use EJS

    E-Print Network [OSTI]

    Wee, Loo Kang; Chew, Charles; Wong, Darren; Tan, Samuel

    2015-01-01T23:59:59.000Z

    This paper reports a computer model- simulation created using Easy Java Simulation (EJS) for learners to visualize how the steady-state amplitude of a driven oscillating system varies with the frequency of the periodic driving force. The simulation shows (N=100) identical spring-mass systems being subjected to (1) periodic driving force of equal amplitude but different driving frequencies and (2) different amount of damping. The simulation aims to create a visually intuitive way of understanding how the series of amplitude versus driving frequency graphs are obtained by showing how the displacement of the system changes over time as it transits from the transient to the steady state. A suggested how to use the model is added to help educators and students in their teaching and learning, where we explained the theoretical steady state equation, time conditions when the model starts allowing data recording of maximum amplitudes to closely match the theoretical equation and steps to collect different runs of deg...

  9. Bipartite Q-polynomial distance-regular graphs and uniform posets

    E-Print Network [OSTI]

    Miklavic, Stefko

    2011-01-01T23:59:59.000Z

    Let $\\G$ denote a bipartite distance-regular graph with vertex set $X$ and diameter $D \\ge 3$. Fix $x \\in X$ and let $L$ (resp. $R$) denote the corresponding lowering (resp. raising) matrix. We show that each $Q$-polynomial structure for $\\G$ yields a certain linear dependency among $RL^2$, $LRL$, $L^2R$, $L$. Define a partial order $\\le$ on $X$ as follows. For $y,z \\in X$ let $y \\le z$ whenever $\\partial(x,y)+\\partial(y,z)=\\partial(x,z)$, where $\\partial$ denotes path-length distance. We determine whether the above linear dependency gives this poset a uniform or strongly uniform structure. We show that except for one special case a uniform structure is attained, and except for three special cases a strongly uniform structure is attained.

  10. Using Graph Theory and a Plenoptic Sensor to Recognize Phase Distortions of a Laser Beam

    E-Print Network [OSTI]

    Wu, Chensheng; Davis, Christopher C

    2015-01-01T23:59:59.000Z

    Atmospheric turbulence causes fluctuations in the local refractive index of air that accumulatively disturb a wave's phase and amplitude distribution as it propagates. This impairs the effective range of laser weapons as well as the performance of free space optical (FSO) communication systems. Adaptive optics (AO) can be applied to effectively correct wavefront distortions in weak turbulence situations. However, in strong or deep turbulence, where scintillation and beam breakup are common phenomena, traditional wavefront sensing techniques such as the use of Shack-Hartmann sensors lead to incorrect results. Consequently, the performance of AO systems will be greatly compromised. We propose a new approach that can determine the major phase distortions in a beam instantaneously and guide an AO device to compensate for the phase distortion in a few iterations. In our approach, we use a plenoptic wavefront sensor to image the distorted beam into its 4D phase space. A fast reconstruction algorithm based on graph ...

  11. A Feynman-Kac-Itô Formula for magnetic Schrödinger operators on graphs

    E-Print Network [OSTI]

    Batu Güneysu; Matthias Keller; Marcel Schmidt

    2015-05-21T23:59:59.000Z

    In this paper we prove a Feynman-Kac-It\\^{o} formula for magnetic Schr\\"odinger operators on arbitrary weighted graphs. To do so, we have to provide a natural and general framework both on the operator theoretic and the probabilistic side of the equation. On the operator side we identify a very general class of potentials that allows the definition of magnetic Schr\\"odinger operators. On the probabilistic side, we introduce an appropriate notion of stochastic line integrals with respect to magnetic potentials. Apart from linking the world of discrete magnetic operators with the probabilistic world through the Feynman-Kac-It\\^{o} formula, the insights from this paper gained on both sides should be of an independent interest. As applications of the Feynman-Kac-It\\^{o} formula, we prove a Kato inequality, a Golden-Thompson inequality and an explicit representation of the quadratic form domains corresponding to a large class of potentials.

  12. Approximate inference on planar graphs using loop calculus and belief progagation

    SciTech Connect (OSTI)

    Chertkov, Michael [Los Alamos National Laboratory; Gomez, Vicenc [RADBOUD UNIV; Kappen, Hilbert [RADBOUD UNIV

    2009-01-01T23:59:59.000Z

    We introduce novel results for approximate inference on planar graphical models using the loop calculus framework. The loop calculus (Chertkov and Chernyak, 2006b) allows to express the exact partition function Z of a graphical model as a finite sum of terms that can be evaluated once the belief propagation (BP) solution is known. In general, full summation over all correction terms is intractable. We develop an algorithm for the approach presented in Chertkov et al. (2008) which represents an efficient truncation scheme on planar graphs and a new representation of the series in terms of Pfaffians of matrices. We analyze in detail both the loop series and the Pfaffian series for models with binary variables and pairwise interactions, and show that the first term of the Pfaffian series can provide very accurate approximations. The algorithm outperforms previous truncation schemes of the loop series and is competitive with other state-of-the-art methods for approximate inference.

  13. Eigenfunctions of Unbounded Support for Embedded Eigenvalues of Locally Perturbed Periodic Graph Operators

    E-Print Network [OSTI]

    Stephen P. Shipman

    2014-04-24T23:59:59.000Z

    It is known that, if a locally perturbed periodic self-adjoint operator on a combinatorial or quantum graph admits an eigenvalue embedded in the continuous spectrum, then the associated eigenfunction is compactly supported--that is, if the Fermi surface is irreducible, which occurs generically in dimension two or higher. This article constructs a class of operators whose Fermi surface is reducible for all energies by coupling several periodic systems. The components of the Fermi surface correspond to decoupled spaces of hybrid states, and in certain frequency bands, some components contribute oscillatory hybrid states (corresponding to spectrum) and other components contribute only exponential ones. This separation allows a localized defect to suppress the oscillatory (radiation) modes and retain the evanescent ones, thereby leading to embedded eigenvalues whose associated eigenfunctions decay exponentially but are not compactly supported.

  14. Designing a graph-based approach to landscape ecological assessment of linear infrastructures

    SciTech Connect (OSTI)

    Girardet, Xavier, E-mail: xavier.girardet@univ-fcomte.fr; Foltête, Jean-Christophe, E-mail: jean-christophe.foltete@univ-fcomte.fr; Clauzel, Céline, E-mail: celine.clauzel@univ-fcomte.fr

    2013-09-15T23:59:59.000Z

    The development of major linear infrastructures contributes to landscape fragmentation and impacts natural habitats and biodiversity in various ways. To anticipate and minimize such impacts, landscape planning needs to be capable of effective strategic environmental assessment (SEA) and of supporting environmental impact assessment (EIA) decisions. To this end, species distribution models (SDMs) are an effective way of making predictive maps of the presence of a given species. In this paper, we propose to combine SDMs and graph-based representation of landscape networks to integrate the potential long-distance effect of infrastructures on species distribution. A diachronic approach, comparing distribution before and after the linear infrastructure is constructed, leads to the design of a species distribution assessment (SDA), taking into account population isolation. The SDA makes it possible (1) to estimate the local variation in probability of presence and (2) to characterize the impact of the infrastructure in terms of global variation in presence and of distance of disturbance. The method is illustrated by assessing the impact of the construction of a high-speed railway line on the distribution of several virtual species in Franche-Comté (France). The study shows the capacity of the SDA to characterize the impact of a linear infrastructure either as a research concern or as a spatial planning challenge. SDAs could be helpful in deciding among several scenarios for linear infrastructure routes or for the location of mitigation measures. -- Highlights: • Graph connectivity metrics were integrated into a species distribution model. • SDM was performed before and after the implementation of linear infrastructure. • The local variation of presence provides spatial indicators of the impact.

  15. Retracts of products of chordal graphs B. Bresar1, J. Chalopin2, V. Chepoi2, M. Kovse1, A. Labourel2, and Y. Vax`es2

    E-Print Network [OSTI]

    Chepoi, Victor

    2, and Y. Vax`es2 1Faculty of Natural Sciences and Mathematics University of Maribor, Koroska cesta {chalopin,chepoi,labourel,vaxes}@lif.univ-mrs.fr Abstract. In this note, we characterize the graphs G

  16. A causal model of linkages among strategy, structure, and performance using directed acyclic graphs: A manufacturing subset of Fortune 500 industrials 1990-1998 

    E-Print Network [OSTI]

    Chong, Hogun

    2004-09-30T23:59:59.000Z

    This research explored the causal relationships among strategies, corporate structure, and performance of the largest U.S. non-financial firms using Directed Acyclic Graphs (DAGs). Corporate strategies and structure have ...

  17. On the critical parameters of the $q\\ge4$ random-cluster model on isoradial graphs

    E-Print Network [OSTI]

    Vincent Beffara; Hugo Duminil-Copin; Stanislav Smirnov

    2015-07-06T23:59:59.000Z

    The critical surface for random-cluster model with cluster-weight $q\\ge 4$ on isoradial graphs is identified using parafermionic observables. Correlations are also shown to decay exponentially fast in the subcritical regime. While this result is restricted to random-cluster models with $q\\ge 4$, it extends the recent theorem of the two first authors to a large class of planar graphs. In particular, the anisotropic random-cluster model on the square lattice is shown to be critical if $\\frac{p_vp_h}{(1-p_v)(1-p_h)}=q$, where $p_v$ and $p_h$ denote the horizontal and vertical edge-weights respectively. We also mention consequences for Potts models.

  18. Relating Doubly-Even Error-Correcting Codes, Graphs, and Irreducible Representations of N-Extended Supersymmetry

    E-Print Network [OSTI]

    C. F. Doran; M. G. Faux; S. J. Gates Jr; T. Hubsch; K. M. Iga; G. D. Landweber

    2008-05-31T23:59:59.000Z

    Previous work has shown that the classification of indecomposable off-shell representations of N-supersymmetry, depicted as Adinkras, may be factored into specifying the topologies available to Adinkras, and then the height-assignments for each topological type. The latter problem being solved by a recursive mechanism that generates all height-assignments within a topology, it remains to classify the former. Herein we show that this problem is equivalent to classifying certain (1) graphs and (2) error-correcting codes.

  19. Complete-Graph Tensor Network States: A New Fermionic Wave Function Ansatz for Molecules

    E-Print Network [OSTI]

    Konrad H Marti; Bela Bauer; Markus Reiher; Matthias Troyer; Frank Verstraete

    2010-04-29T23:59:59.000Z

    We present a new class of tensor network states that are specifically designed to capture the electron correlation of a molecule of arbitrary structure. In this ansatz, the electronic wave function is represented by a Complete-Graph Tensor Network (CGTN) ansatz which implements an efficient reduction of the number of variational parameters by breaking down the complexity of the high-dimensional coefficient tensor of a full-configuration-interaction (FCI) wave function. We demonstrate that CGTN states approximate ground states of molecules accurately by comparison of the CGTN and FCI expansion coefficients. The CGTN parametrization is not biased towards any reference configuration in contrast to many standard quantum chemical methods. This feature allows one to obtain accurate relative energies between CGTN states which is central to molecular physics and chemistry. We discuss the implications for quantum chemistry and focus on the spin-state problem. Our CGTN approach is applied to the energy splitting of states of different spin for methylene and the strongly correlated ozone molecule at a transition state structure. The parameters of the tensor network ansatz are variationally optimized by means of a parallel-tempering Monte Carlo algorithm.

  20. A Quantum Annealing Approach for Fault Detection and Diagnosis of Graph-Based Systems

    E-Print Network [OSTI]

    Alejandro Perdomo-Ortiz; Joseph Fluegemann; Sriram Narasimhan; Rupak Biswas; Vadim N. Smelyanskiy

    2014-10-02T23:59:59.000Z

    Diagnosing the minimal set of faults capable of explaining a set of given observations, e.g., from sensor readouts, is a hard combinatorial optimization problem usually tackled with artificial intelligence techniques. We present the mapping of this combinatorial problem to quadratic unconstrained binary optimization (QUBO), and the experimental results of instances embedded onto a quantum annealing device with 509 quantum bits. Besides being the first time a quantum approach has been proposed for problems in the advanced diagnostics community, to the best of our knowledge this work is also the first research utilizing the route Problem $\\rightarrow$ QUBO $\\rightarrow$ Direct embedding into quantum hardware, where we are able to implement and tackle problem instances with sizes that go beyond previously reported toy-model proof-of-principle quantum annealing implementations; this is a significant leap in the solution of problems via direct-embedding adiabatic quantum optimization. We discuss some of the programmability challenges in the current generation of the quantum device as well as a few possible ways to extend this work to more complex arbitrary network graphs.

  1. PyDecay/GraphPhys: A Unified Language and Storage System for Particle Decay Process Descriptions

    SciTech Connect (OSTI)

    Dunietz, Jesse N.; /MIT /SLAC

    2011-06-22T23:59:59.000Z

    To ease the tasks of Monte Carlo (MC) simulation and event reconstruction (i.e. inferring particle-decay events from experimental data) for long-term BaBar data preservation and analysis, the following software components have been designed: a language ('GraphPhys') for specifying decay processes, common to both simulation and data analysis, allowing arbitrary parameters on particles, decays, and entire processes; an automated visualization tool to show graphically what decays have been specified; and a searchable database storage mechanism for decay specifications. Unlike HepML, a proposed XML standard for HEP metadata, the specification language is designed not for data interchange between computer systems, but rather for direct manipulation by human beings as well as computers. The components are interoperable: the information parsed from files in the specification language can easily be rendered as an image by the visualization package, and conversion between decay representations was implemented. Several proof-of-concept command-line tools were built based on this framework. Applications include building easier and more efficient interfaces to existing analysis tools for current projects (e.g. BaBar/BESII), providing a framework for analyses in future experimental settings (e.g. LHC/SuperB), and outreach programs that involve giving students access to BaBar data and analysis tools to give them a hands-on feel for scientific analysis.

  2. Central limit theorems, Lee-Yang zeros, and graph-counting polynomials

    E-Print Network [OSTI]

    J. L. Lebowitz; B. Pittel; D. Ruelle; E. R. Speer

    2014-08-18T23:59:59.000Z

    We consider the asymptotic normalcy of families of random variables $X$ which count the number of occupied sites in some large set. We write $Prob(X=m)=p_mz_0^m/P(z_0)$, where $P(z)$ is the generating function $P(z)=\\sum_{j=0}^{N}p_jz^j$ and $z_0>0$. We give sufficient criteria, involving the location of the zeros of $P(z)$, for these families to satisfy a central limit theorem (CLT) and even a local CLT (LCLT); the theorems hold in the sense of estimates valid for large $N$ (we assume that $Var(X)$ is large when $N$ is). For example, if all the zeros lie in the closed left half plane then $X$ is asymptotically normal, and when the zeros satisfy some additional conditions then $X$ satisfies an LCLT. We apply these results to cases in which $X$ counts the number of edges in the (random) set of "occupied" edges in a graph, with constraints on the number of occupied edges attached to a given vertex. Our results also apply to systems of interacting particles, with $X$ counting the number of particles in a box $\\Lambda$ whose size approaches infinity; $P(z)$ is then the grand canonical partition function and its zeros are the Lee-Yang zeros.

  3. Graph-theoretic analysis of discrete-phase-space states for condition change detection and quantification of information

    DOE Patents [OSTI]

    Hively, Lee M.

    2014-09-16T23:59:59.000Z

    Data collected from devices and human condition may be used to forewarn of critical events such as machine/structural failure or events from brain/heart wave data stroke. By monitoring the data, and determining what values are indicative of a failure forewarning, one can provide adequate notice of the impending failure in order to take preventive measures. This disclosure teaches a computer-based method to convert dynamical numeric data representing physical objects (unstructured data) into discrete-phase-space states, and hence into a graph (structured data) for extraction of condition change.

  4. Leaf-to-leaf distances and their moments in finite and infinite m-ary tree graphs

    E-Print Network [OSTI]

    Andrew M. Goldsborough; S. Alex Rautu; Rudolf A. Römer

    2015-04-17T23:59:59.000Z

    We study the leaf-to-leaf distances on full and complete m-ary graphs using a recursive approach. In our formulation, leaves are ordered along a line. We find explicit analytical formulae for the sum of all paths for arbitrary leaf-to-leaf distance r as well as the average path lengths and the moments thereof. We show that the resulting explicit expressions can be recast in terms of Hurwitz-Lerch transcendants. Results for periodic trees are also given. For incomplete random binary trees, we provide first results by numerical techniques; we find a rapid drop of leaf-to-leaf distances for large r.

  5. The Author (2007). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org 1 RAGPOOLS: RNA-As-Graph-Pools A Web Server for Assisting the

    E-Print Network [OSTI]

    Schlick, Tamar

    2007-01-01T23:59:59.000Z

    , please email: journals.permissions@oxfordjournals.org 1 RAGPOOLS: RNA-As-Graph-Pools ­ A Web Server: Our RNA-As-Graph-Pools (RAGPOOLS) web server offers a theoretical companion tool for RNA in vitro. The companion RAGPOOLS web server ("Designer" component) provides optimized starting sequences, mixing matrices

  6. Graphe de connectivit crbrale et longue dpendance Florent CHATELAIN1, Sophie ACHARD1, Cdric GOUY-PAILLER2, Olivier MICHEL1, Pierre Olivier AMBLARD1,3

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Graphe de connectivité cérébrale et longue dépendance Florent CHATELAIN1, Sophie ACHARD1, Cédric GOUY-PAILLER2, Olivier MICHEL1, Pierre Olivier AMBLARD1,3 1 GIPSA-lab, CNRS, Université de Grenoble, 2 sans les progrès réalisés dans le domaine de 1S. Achard est partiellement financée par l'ANR 2010 JCJC

  7. arXiv:1307.1718v1[cs.IR]5Jul2013 Graph-based Approach to Automatic Taxonomy Generation (GraBTax)

    E-Print Network [OSTI]

    Giles, C. Lee

    arXiv:1307.1718v1[cs.IR]5Jul2013 Graph-based Approach to Automatic Taxonomy Generation (Gra in optimizing the structure of the taxonomy. To automatically generate topic-dependent taxonomies from a large with Wikipedia categories. 1 Introduction A taxonomy organizes concepts into a hierarchical structure, where

  8. The graphs at right show overall variability distribution estimated for the Pentium D 800 series (near) and the T1 Niagara (far) using the FPGA data

    E-Print Network [OSTI]

    Renau, Jose

    RESULTS The graphs at right show overall variability distribution estimated for the Pentium D 800 where a core no longer works properly. In the Sun T1 Niagara cores this is done with a built-in- self processors we record the temperature at which the failure occurred and adjust to the frequencies

  9. FOUNDATIONS IN ABSTRACT MATHEMATICS MARCH 19, 2012 1. Find a maximum matching and a minimum cover in the following bipartite graph: (A)

    E-Print Network [OSTI]

    Wagner, Stephan

    , and each man ranks all women from best to worst. Now each woman should marry one of the men (and vice versa such that increasing subsequences are chains and decreasing subsequences are antichains (or vice versa).] 5. A graph town, there is an equal number of men and women. Each woman ranks all (C) men from best to worst

  10. 2188 IEEE TRANSACTIONS ON INFORMATION THEORY, VOL. 57, NO. 4, APRIL 2011 Graph-Based Decoding in the Presence of ISI

    E-Print Network [OSTI]

    Siegel, Paul H.

    in the Presence of ISI Mohammad H. Taghavi, Member, IEEE, and Paul H. Siegel, Fellow, IEEE Abstract--We propose a new graph representation for ISI channels that can be used for combined equalization and decoding to certain two-dimensional ISI chan- nels. However, for some other channel impulse responses, both decoders

  11. Design and analysis of algorithms and data structures for the efficient solution of graph theoretic problems on MIMD computers

    SciTech Connect (OSTI)

    Quinn, M.J.

    1983-01-01T23:59:59.000Z

    The problem of developing efficient algorithms and data structures to solve graph theoretic problems on tightly-coupled MIMD comuters is addressed. Several approaches to parallelizing a serial algorithm are examined. A technique is developed which allows the prediction of the expected execution time of some kinds of parallel algorithms. This technique can be used to determine which parallel algorithm is best for a particular application. Two parallel approximate algorithms for the Euclidean traveling salesman problem are designed and analyzed. The algorithms are parallelizations of the farthest-insertion heuristic and Karp's partitioning algorithm. Software lockout, the delay of processes due to contention for shared data structure, can be a significant hindrance to obtaining satisfactory speedup. Using the tactics of indirection and replication, new data structures are devised which can reduce the severity of software lockout. Finally, an upper bound to the speedup of parallel branch-and-bound algorithms which use the best-bound search strategy is determined.

  12. The dynamic, resource-constrained shortest path problem on an acyclic graph with application in column generation and literature review on sequence-dependent scheduling

    E-Print Network [OSTI]

    Zhu, Xiaoyan

    2007-04-25T23:59:59.000Z

    -5).....................................................................................35 6 EP: expanding (, )R RR to form (, )E EE............................................................36 7 An example of expanded graph E ...............................................................................38 8 OA...? ) is associated with set of nonnegative discrete valued resources, . A cost ij and a discrete-valued resource-requirement vector ij =u ( 1 ,,ijuu? ) are associated with each arc ( , )ij A? . Traversing arc ( , )ij consumes an amount ijr of resource r...

  13. Specifying MultipleViewed Software Requirements With Conceptual Graphs Title Pages

    E-Print Network [OSTI]

    Delugach, Harry S.

    Planning Office. He was a computing analyst for the Department of Energy implementing a distributed engineering honor society Tau Beta Pi (VA A) in 1987, and is a member of the ACM and the IEEE Computer Society

  14. Liver segmentation in contrast enhanced CT data using graph cuts and interactive 3D segmentation refinement methods

    SciTech Connect (OSTI)

    Beichel, Reinhard; Bornik, Alexander; Bauer, Christian; Sorantin, Erich [Departments of Electrical and Computer Engineering and Internal Medicine, Iowa Institute for Biomedical Imaging, University of Iowa, Iowa City, Iowa 52242 (United States); Institute for Computer Graphics and Vision, Graz University of Technology, Inffeldgasse 16, A-8010 Graz (Austria); Department of Electrical and Computer Engineering, Iowa Institute for Biomedical Imaging, University of Iowa, Iowa City, Iowa 52242 (United States); Department of Radiology, Medical University Graz, Auenbruggerplatz 34, A-8010 Graz (Austria)

    2012-03-15T23:59:59.000Z

    Purpose: Liver segmentation is an important prerequisite for the assessment of liver cancer treatment options like tumor resection, image-guided radiation therapy (IGRT), radiofrequency ablation, etc. The purpose of this work was to evaluate a new approach for liver segmentation. Methods: A graph cuts segmentation method was combined with a three-dimensional virtual reality based segmentation refinement approach. The developed interactive segmentation system allowed the user to manipulate volume chunks and/or surfaces instead of 2D contours in cross-sectional images (i.e, slice-by-slice). The method was evaluated on twenty routinely acquired portal-phase contrast enhanced multislice computed tomography (CT) data sets. An independent reference was generated by utilizing a currently clinically utilized slice-by-slice segmentation method. After 1 h of introduction to the developed segmentation system, three experts were asked to segment all twenty data sets with the proposed method. Results: Compared to the independent standard, the relative volumetric segmentation overlap error averaged over all three experts and all twenty data sets was 3.74%. Liver segmentation required on average 16 min of user interaction per case. The calculated relative volumetric overlap errors were not found to be significantly different [analysis of variance (ANOVA) test, p = 0.82] between experts who utilized the proposed 3D system. In contrast, the time required by each expert for segmentation was found to be significantly different (ANOVA test, p = 0.0009). Major differences between generated segmentations and independent references were observed in areas were vessels enter or leave the liver and no accepted criteria for defining liver boundaries exist. In comparison, slice-by-slice based generation of the independent standard utilizing a live wire tool took 70.1 min on average. A standard 2D segmentation refinement approach applied to all twenty data sets required on average 38.2 min of user interaction and resulted in statistically not significantly different segmentation error indices (ANOVA test, significance level of 0.05). Conclusions: All three experts were able to produce liver segmentations with low error rates. User interaction time savings of up to 71% compared to a 2D refinement approach demonstrate the utility and potential of our approach. The system offers a range of different tools to manipulate segmentation results, and some users might benefit from a longer learning phase to develop efficient segmentation refinement strategies. The presented approach represents a generally applicable segmentation approach that can be applied to many medical image segmentation problems.

  15. Graphs, Strings, and Actions

    E-Print Network [OSTI]

    2010-04-01T23:59:59.000Z

    c© Springer Science+Business Media, LLC 2009 ...... [MS1] J. E. McClure and J. H. Smith. A solution of ... [MS3] James E. McClure and Jeffrey H. Smith.

  16. Graph algorithms experimentation facility

    E-Print Network [OSTI]

    Sonom, Donald George

    1994-01-01T23:59:59.000Z

    DRAWADJMAT 2 ~e ~l 2. ~f ~2 2 ~t ~& [g H 2 O? Z Mwd a P d ed d Aid~a sae R 2-BE& T C dbms Fig. 2. External Algorithm Handler The facility is menu driven and implemented as a client to XAGE. Our implementation follows very closely the functionality...

  17. PDSF Utilization Graphs

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)IntegratedSpeeding access toTest andOptimize832 2.860Selected Announcements

  18. NOTE: This graph charts the pH level of the water leaving active chemical drain neutralization system in the Natural Science and Engineering Cleanroom laboratory on the UTD campus. It also monitors the

    E-Print Network [OSTI]

    Lee, Jeong-Bong

    NOTE: This graph charts the pH level of the water leaving active chemical drain neutralization 6 8 10 12 14 pHDeviation(8-pH) pHatDischargeTank Date NSERL Back Dock Chemical Neutralization p

  19. AN ASPECT OF A DIDACTICAL PATH FOR APPROACHING THE CONCEPT OF FUNCTION: THE QUALITATIVE INTERPRETATION OF A GRAPH

    E-Print Network [OSTI]

    Spagnolo, Filippo

    156 AN ASPECT OF A DIDACTICAL PATH FOR APPROACHING THE CONCEPT OF FUNCTION: THE QUALITATIVE uncertainties and difficulties when teaching it (Even, 1993). At the middle school level, it seems didactically and their representations. From a didactical point of view, this sets the problem of how to lead the student to put

  20. Automatic Online Haptic Graph Construction

    E-Print Network [OSTI]

    Yu, W.; Cheung, K.; Brewster, S.A.

    Yu,W. Cheung,K. Brewster,S.A. In Proceedings of Eurohaptics 2002 (Edinburgh, UK), Edinburgh University pp 128-133 Academic Press

  1. 38 Chapteri - Functions and Graphs

    E-Print Network [OSTI]

    will describe the average pollution, in particles of ... a) Predict the pollution in 2007, 2010, and 2020. ..... completely drained of air; the minimum volume of the.

  2. Graphs in R and Bioconductor

    E-Print Network [OSTI]

    Spang, Rainer

    biggest: size ~ log(n)). degrees of separation: log(n). Erdös and Rényi 1960 #12;Small worlds Clustering networks - scientific collaboration networks - WWW - company ownership in Germany - ,,6 degrees of Kevin

  3. HLTNAACL 06 TextGraphs

    E-Print Network [OSTI]

    Radev, Dragomir R.

    of the Workshop #12; Production and Manufacturing by Omnipress Inc. 2600 Anderson Street Madison, WI 53704 c #2006 of confidence provided by her quick and enthusiastic acceptance. Rada Mihalcea and Dragomir Radev June 2006 iii, Cornell University Patrick Pantel, USC / Information Sciences Institute Paul Tarau, University of North

  4. Phylogenetic Toric Varieties on Graphs

    E-Print Network [OSTI]

    Buczynska, Weronika J.

    2010-10-12T23:59:59.000Z

    ?s book [17]. This theory assumes that the algebraic group G that acts on X is reductive and the action has a linearization with respect to some line bundle on X . Depending on the line bundle the set of (semi-)stable points is determined... for a normal projective variety X with an action of an algebraic torus T. Our main reference is Section 5 and 6 of [2], although the setup we use may seem to be slightly more general then the one found in [2]. This is because instead of linearizing...

  5. Analysis of beacon triangulation in random graphs

    E-Print Network [OSTI]

    Kakarlapudi, Geetha

    2005-02-17T23:59:59.000Z

    ( in hops ) Percentage of nodes p=0.0007 (a) 0 0.1 0.2 0.3 0.4 0.5 0.6 0 2 4 6 8 Distance ( in hops ) Percentage of nodes p=0.001 (b) Fig. 14. Shortest path distribution of nodes with equal distance vectors: (a) n = 10000, lambda = 7; (b) n = 10000, lambda...

  6. Completely distinguishable projections of spatial graphs

    E-Print Network [OSTI]

    Nikkuni, Ryo

    . 1.1. We can obtain the eight spatial embeddings g1, g2, . . . , g8 of G from ^f as illustrated 2 3 4 5 6 g1 g2 g3 g4 g5 g6 g7 g8 Fig. 1.2. 2 #12;2. Completely distinguishable projections

  7. Efficient Simulation of Critical Synchronous Dataflow Graphs

    E-Print Network [OSTI]

    Bhattacharyya, Shuvra S.

    -oriented tools incorporate SDF semantics, including ADS from Agilent [14], the Autocoding Toolset from MCCI [15

  8. Detecting Network Vulnerabilities Through Graph Theoretical Methods

    E-Print Network [OSTI]

    Geddes, Cameron Guy Robinson

    vulnerabilities in power networks is an important prob- lem, as even a small number of vulnerable connections can benchmark power networks. 1 Introduction The electric power grid network is susceptible to power outages northeast and Canada, which affected an estimated 50 million people, causing over $6 billion in damage

  9. Graph Layout Techniques and Multidimensional Data Analysis

    E-Print Network [OSTI]

    Jan de Leeuw; George Michailides

    2011-01-01T23:59:59.000Z

    Society, 13: [57] E.J. Wegman. Hyperdimensional dataInselburg and Dimsdale [33], Wegman [57]. In these plots, we

  10. HLT-NAACL 06 TextGraphs

    E-Print Network [OSTI]

    Radev, Dragomir R.

    of the Workshop #12;Production and Manufacturing by Omnipress Inc. 2600 Anderson Street Madison, WI 53704 c 2006 of confidence provided by her quick and enthusiastic acceptance. Rada Mihalcea and Dragomir Radev June 2006 iii, Cornell University Patrick Pantel, USC / Information Sciences Institute Paul Tarau, University of North

  11. Analysis of Link Graph Compression Techniques

    E-Print Network [OSTI]

    Hannah, D.; Macdonald, C.; Ounis, I.

    Hannah,D. Macdonald,C. Ounis,I. In Proceedings of the 30th European Conference on Information Retrieval (ECIR 2008), Glasgow, 30th March - 3rd April 2008. LNCS, Springer

  12. Graphs and Combinatorial Representations of Stochastic Processes

    E-Print Network [OSTI]

    Ting, Daniel

    2012-01-01T23:59:59.000Z

    Jordan, M. J. Beal, and D. M. Blei. Hierarchical DirichletStatistical Science, D. M. Blei and P. Frazier. DistanceMachine Learning, 2010. D. M. Blei, T. L. Griffiths, and M.

  13. Convex Optimization of Graph Laplacian Eigenvalues

    E-Print Network [OSTI]

    with Persi Diaconis, Arpita Ghosh, Seung-Jean Kim, Sanjay Lall, Pablo Parrilo, Amin Saberi, Jun Sun, Lin Xiao

  14. Diffusion and clustering on large graphs

    E-Print Network [OSTI]

    Tsiatas, Alexander

    2012-01-01T23:59:59.000Z

    Jennifer Chayes, and Amin Saberi. “On the spread of virusesGanesh, and Amin Saberi. “How to distribute antidote toMontanari and Amin Saberi. “Convergence to equilibrium in

  15. Convex Optimization of Graph Laplacian Eigenvalues

    E-Print Network [OSTI]

    Persi Diaconis, Arpita Ghosh, Seung-Jean Kim, Sanjay Lall, Pablo Parrilo, Amin Saberi. Jun Sun, and Lin

  16. Catalogs of Regular Graphs Robert A. Beezer

    E-Print Network [OSTI]

    Beezer, Robert A.

    Science University of Puget Sound Tacoma, Washington 98416 May 12, 1992 Abstract Exhaustive catalogs

  17. A Parallel Graph Partitioner for STAPL

    E-Print Network [OSTI]

    Castet, Nicolas

    2013-04-26T23:59:59.000Z

    high-level framework to develop parallel applications. One of the first steps of a parallel application is to partition and distribute the data throughout the system. An important data structure for parallel applications to store large amounts of data...

  18. Graph Implementations for Nonsmooth Convex Programs

    E-Print Network [OSTI]

    2007-09-07T23:59:59.000Z

    1 Stanford University mcgrant@stanford.edu. 2 Stanford University ... large library of common convex and concave functions, both smooth and non- smooth, and ...

  19. Graph regularization methods for Web spam detection

    E-Print Network [OSTI]

    Abernethy, Jacob; Chapelle, Olivier; Castillo, Carlos

    2010-01-01T23:59:59.000Z

    An introduction to the conjugate gradient method without theonly implemented the conjugate gradient method. Note onemployed was the conjugate gradient method, de- scribed in

  20. MIT Lincoln Laboratory Linear Algebraic Graph Algorithms

    E-Print Network [OSTI]

    Kepner, Jeremy

    & scale ­ ~ 103 seconds needed for effective CONOPS (1000x improvement) Planned system capability (over