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Canonizing Graphs of Bounded Tree Width in Logspace

Canonizing Graphs of Bounded Tree Width in Logspace Graph canonization is the problem of computing a unique representative, a canon, from the isomorphism class of a given graph. This implies that two graphs are isomorphic exactly if their canons are equal. We show that graphs of bounded tree width can be canonized by logarithmic-space (logspace) algorithms. This implies that the isomorphism problem for graphs of bounded tree width can be decided in logspace. In the light of isomorphism for trees being hard for the complexity class logspace, this makes the ubiquitous class of graphs of bounded tree width one of the few classes of graphs for which the complexity of the isomorphism problem has been exactly determined. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png ACM Transactions on Computation Theory (TOCT) Association for Computing Machinery

Canonizing Graphs of Bounded Tree Width in Logspace

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Publisher
Association for Computing Machinery
Copyright
Copyright © 2017 ACM
ISSN
1942-3454
eISSN
1942-3462
DOI
10.1145/3132720
Publisher site
See Article on Publisher Site

Abstract

Graph canonization is the problem of computing a unique representative, a canon, from the isomorphism class of a given graph. This implies that two graphs are isomorphic exactly if their canons are equal. We show that graphs of bounded tree width can be canonized by logarithmic-space (logspace) algorithms. This implies that the isomorphism problem for graphs of bounded tree width can be decided in logspace. In the light of isomorphism for trees being hard for the complexity class logspace, this makes the ubiquitous class of graphs of bounded tree width one of the few classes of graphs for which the complexity of the isomorphism problem has been exactly determined.

Journal

ACM Transactions on Computation Theory (TOCT)Association for Computing Machinery

Published: Oct 4, 2017

Keywords: Algorithmic graph theory

References