Undecidable Equivalences for Basic Process Algebra

Abstract

A recent theorem shows that strong bisimilarity is decidable for the class of normed BPA processes, which correspond to a class of context-free grammars generating the ϵ-free context-free languages. Huynh and Tian (Technical Report UTDCS-31-90, University of Texas at Dallas, 1990) have shown that readiness and failure equivalence are undecidable for BPA processes. In this paper we examine all other equivalences in the linear/branching time hierarchy and show that none of them are decidable for normed BPA processes.