Decidability of Bisimulation Equivalence of Context-free Processes Extends to Processes Deened over Bpa

In CHS92] was proved that (strong) bisimulation equivalence is de-cidable for all context-free processes. We reduce eeectively the question of bisimulation equivalence of processes in BPA to that of context-free processes, by interpreting the deadlocking process as a process which iterates a fresh action forever. This shows that bisimulation is also decidable for BPA. 1 Introduction In BBK87, BBK93] it was proved that bisimulation equivalence is decid-able for normed context-free processes, also known as normed processes over BPA. In that remarkable paper it was shown for the rst time that context-free processes express some nite periodicities which allow an eeective comparison. In Cau90, HS91, Gro92] simpler proofs have been given of the same result. In HJM94] a polynomial time algorithm for deciding bisimulation for normed context-free processes has been given. In CHS92] the previous result was extended by showing decidability of bisimulation equivalence for all context-free processes, also known as processes over BPA. The proof is very elegant, using a deep insight in the Research supported by Esprit BRA 7166 concur 2.