Expansive-Bisimulation for Context-Free Processes

Abstract

Through the notion of expansive-bisimulation, in this paper we give a finite characterization of bisimulation equivalence for contextfree processes, i.e. we show that two context-free processes are bisimulation equivalent if and only if there is a finite expansive-bisimulation which contains them. This immediately suggests the set of finite expansivebisimulation as a complete class of verifiable evidence for bisimulation equality of context-free processes. Compared with the well known result that two context-free processes are bisimulation equivalent if and only if there is a finite self-bisimulation which relates them, the new result made improvement in the sense that whether a finite relation is an expansive-bisimulation is decidable while whether a finite relation is a self-bisimulation is only semi-decidable.