On the nlog n isomorphism technique (A Preliminary Report)

Abstract

Tarjan has given an algorithm for deciding isomorphism of two groups of order n (given as multiplication tables) which runs in O(n(log2n+O(1)) steps where n is the order of the groups. Tarjan uses the fact that a group of n is generated by log n elements. In this paper, we show that Tarjan's technique generalizes to isomorphism of quasigroups, latin squares, Steiner systems, and many graphs generated from these combinatorial objects.