Title
Graph Isomorphism for K_{3, 3}-free and K_5-free graphs is in Log-space
Abstract
Graph isomorphism is an important and widely studied computational problem with a yet unsettled complexity. However, the exact complexity is known for isomorphism of various classes of graphs. Recently, (8) proved that planar isomorphism is complete for log-space. We extend this result further to the classes of graphs which exclude K3,3 or K5 as a minor, and give a log-space algorithm. Our algorithm decomposes K3,3 minor-free graphs into biconnected and those further into tricon- nected components, which are known to be either planar or K5 components (20). This gives a tricon- nected component tree similar to that for planar graphs. An extension of the log-space algorithm of (8) can then be used to decide the isomorphism problem. For K5 minor-free graphs, we consider 3-connected components. These are either planar or isomor- phic to the four-rung mobius ladder on 8 vertices or, with a further decomposition, one obtains planar 4-connected components (9). We give an algorithm to get a unique decomposition of K5 minor-free graphs into bi-, tri- and 4-connected components, and construct trees, accordingly. Since the algorithm of (8) does not deal with four-connected component trees, it needs to be modified in a quite non-trivial way.
Year
DOI
Venue
2009
10.4230/LIPIcs.FSTTCS.2009.2314
FSTTCS
Keywords
Field
DocType
planar graph,graph isomorphism,connected component
Discrete mathematics,Combinatorics,Indifference graph,Modular decomposition,Graph isomorphism,Graph homomorphism,Chordal graph,Induced subgraph isomorphism problem,Pathwidth,Planar graph,Mathematics
Conference
Citations 
PageRank 
References 
9
0.51
9
Authors
4
Name
Order
Citations
PageRank
Samir Datta120019.82
Prajakta Nimbhorkar217015.04
Thomas Thierauf328833.59
Fabian Wagner4203.87