 
Summary: PhDTW Colloquium
Nov 12, 15:4516:45, Zilverling 2126
Speaker 1: Matthijs Bomhoff
on
Spaceefficient Recognition of Perfect
Elimination Bipartite Graphs
When applying Gaussian elimination to a sparse matrix, it is desirable to avoid turning zeros into non
zeros to preserve the sparsity. The class of perfect elimination bipartite graphs is closely related to
square matrices that Gaussian elimination can be applied to without turning any zero into a nonzero
in the process. Existing literature on the recognition of this class of graphs and matrices (and finding a
suitable set of corresponding pivots) mainly focusses on the time complexity of this problem. However,
when viewed from a practical perspective, the space complexity also deserves our attention: it may not
be worthwhile to look for a suitable set of pivots for a sparse matrix if this requires a `dense' amount of
space. This talk will focus on a new, more spaceefficient algorithm for this problem.
Speaker 2: Didit Adytia
on
Variational Boussinesq Model for Simulation of
Tsunamis and Coastal Waves
We describe the basic ideas of a socalled Variational Boussinesq Model (VBM) which is based on the
Hamiltonian structure of gravity surface waves. By using a rather simple approach to prescribe the profile
