Summary: On External­Memory Planar Depth First Search
Lars Arge 1;? , Ulrich Meyer 2;?? , Laura Toma 1;? ? ? , and Norbert Zeh 3;y
1 Department of Computer Science, Duke University, Durham, NC 27708, USA
flarge,laurag@cs.duke.edu
2 Max­Planck­Institut f¨ur Informatik, Saarbr¨ucken, Germany
umeyer@mpi­sb.mpg.de
3 School of Computer Science, Carleton University, Ottawa, Canada
nzeh@scs.carleton.ca
Abstract. Even though a large number of I/O­efficient graph algo­
rithms have been developed, a number of fundamental problems still
remain open. For example, no space­ and I/O­efficient algorithms are
known for depth­first search or breadth­first search in sparse graphs. In
this paper we present two new results on I/O­efficient depth­first search
in an important class of sparse graphs, namely undirected embedded pla­
nar graphs. We develop a new efficient depth­first search algorithm and
show how planar depth­first search in general can be reduced to planar
breadth­first search. As part of the first result we develop the first I/O­
efficient algorithm for finding a simple cycle separator of a biconnected
planar graph. Together with other recent reducibility results, the sec­
ond result provides further evidence that external memory breadth­first

Source: Arge, Lars - Department of Computer Science, Aarhus Universitet

Collections: Computer Technologies and Information Sciences