Graph isomorphism and automorphism problems are polynomial

Abstract

Many complex questions in biology, physics, and mathematics can be mapped to the graph isomorphism problem and the closely related graph automorphism problem. In particular, these problems appear in the context of network visualization, computational logic, structure recognition, and dynamics of complex systems. Both problems have previously been suspected, but not proven, to be NP-complete. In this paper we propose an algorithm that solves both graph automorphism and isomorphism problems in polynomial time. The algorithm can be easily implemented and thus opens up a wide range of applications.