On External-Memory Planar Depth First Search

Even though a large number of I/O-efficient graph algorithms have been developed, a number of fundamental problems still remain open. For example, no space- and I/O-efficient algorithms are known for depth-first search or breath-first search in sparse graphs. In this paper, we present two new results on I/O-efficient depth-first search in an important class of sparse graphs, namely undirected embedded planar graphs. We develop a new depth-first search algorithm that uses O(sort(N) log(N/M)) I/Os, and show how planar depth-first search can be reduced to planar breadthfirst search in O(sort(N)) I/Os. As part of the first result, we develop the first I/O-efficient algorithm for finding a simple cycle separator of an embedded biconnected planar graph. This algorithm uses O(sort(N)) I/Os. Communicated by Giuseppe Liotta and Ioannis G. Tollis: submitted November 2002; revised January 2003. Lars Arge and Laura Toma supported in part by the National Science Foundation through ESS gra...

• Type: Conference
• Year: 2001
• Where: WADS
• Authors: Lars Arge, Ulrich Meyer, Laura Toma, Norbert Zeh
• Keywords: Algorithms, Depth-first Search, Planar Graph, Sparse Graphs, WADS 2001