Given a class C of Cayley graphs, and given an edge-colored graph G of n vertices and m edges, we are interested in the problem of checking whether there exists an isomorphism φ preserving the colors such that
G is isomorphic by φ to a graph in C colored by the elements of its generating set. In this paper, we give an O(m log n)-time algorithm to check whether G is color-isomorphic to a Cayley graph, improving a previous O(n
4.752 log n) algorithm. In the case where C is the class of the Cayley graphs defined on Abelian groups, we give an optimal O(m)-time algorithm. This algorithm can be extended to check color-isomorphism with Cayley graphs on Abelian groups of given
rank. Finally, we propose an optimal O(m)-time algorithm that tests color-isomorphism between two Cayley graphs on ℤn, i.e., between two circulant graphs. This latter algorithm is extended to an optimal O(n)-time algorithm that tests colorisomorphism between two Abelian Cayley graphs of bounded degree.
This work is supported by an Australian-French cooperation granted by CNRS and ARC. Part of this work has been done while
the three first authors were visiting the Department of Computing of Macquarie University, Sydney. Additional support by Spanish
Research Council (CICYT) under project TIC97-0963, by the CNRS, and by the Aquitaine Region project #98024002.