A Randomized Parallel Algorithm for Planar Graph Isomorphism

We present a parallel randomized algorithm running on aCRCW PRAM, to determine whether two planar graphs are isomorphic, and if so to find the isomorphism. We assume that we have a tree of separators for each planar graph (which can be computed by known algorithms inO(log2n) time withn1+ϵprocessors,...

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Bibliographic Details
Published in:Journal of algorithms Vol. 28; no. 2; pp. 290 - 314
Main Authors: Gazit, Hillel, Reif, John H
Format: Journal Article
Language:English
Published: San Diego, CA Elsevier Inc 01.08.1998
Elsevier
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ISSN:0196-6774, 1090-2678
Online Access:Get full text
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Summary:We present a parallel randomized algorithm running on aCRCW PRAM, to determine whether two planar graphs are isomorphic, and if so to find the isomorphism. We assume that we have a tree of separators for each planar graph (which can be computed by known algorithms inO(log2n) time withn1+ϵprocessors, for any ϵ>0). Ifnis the number of vertices, our algorithm takesO(log(n)) time with processors and with a probability of failure of 1/nat most. The algorithm needs 2·log(m)−log(n)+O(log(n)) random bits. The number of random bits can be decreased toO(log(n)) by increasing the number of processors ton3/2+ϵ, for any ϵ>0. Our parallel algorithm has significantly improved processor efficiency, compared to the previous logarithmic time parallel algorithm of Miller and Reif (Siam J. Comput.20(1991), 1128–1147), which requiresn4randomized processors orn5deterministic processors.
ISSN:0196-6774
1090-2678
DOI:10.1006/jagm.1998.0943