by Ivana Černá, Jitka Stříbrná, December 2000, 26 pages.
FIMU-RS-2000-09. Available as Postscript, PDF.
The purpose of this work is to examine the decidability problem of weak bisimilarity for BPA-processes. It has been known that strong bisimilarity, which may be considered a special case of weak bisimilarity, where the internal (silent) action tau is treated equally to observable actions, is decidable for BPA-processes. For strong bisimilarity, these processes are finitely branching and so for two non-bisimilar processes there exists a level n that distinguishes the two processes. Additionally, from the decidability of whether two processes are equivalent at a given level n, semidecidability of strong non-bisimilarity directly follows. We examine the following two closely related approaches to semidecidability of strong equivalence: