Equivalence checking of non-flat systems is EXPTIME-hard

Abstract

The equivalence checking of systems that are given as a composition of interacting finite-state systems is considered. It is shown that the problem is EXPTIME-hard for any notion of equivalence that lies between bisimulation equivalence and trace equivalence, as conjectured by Rabinovich (1997). The result is proved for parallel composition of finite-state systems where hiding of actions is allowed, and for 1-safe Petri nets. The technique of the proof allows to extend this result easily to other types of non-flat systems.