# Technical Reports

## The report FIMU-RS-96-02

### Comparing Expressibility of Normed BPA and Normed BPP Processes

by Ivana Èerná, Mojmír Køetínský, Antonín Kuèera, This is a full version of the paper which is to be presented at CSL96. June 1996, 28 pages.

FIMU-RS-96-02. Available as Postscript, PDF.

#### Abstract:

We compare the classes of behaviours (transition systems) which can be generated by normed BPA_{\tau} and normed BPP_{\tau} processes. We exactly classify the intersection of these two classes, i.e., the class of transition systems which can be equivalently (up to bisimilarity) described by the syntax of normed BPA_{\tau} and normed BPP_{\tau} processes. We provide such a characterisation for classes of normed BPA and normed BPP processes as well.

Next we show that it is decidable in polynomial time whether for a given normed BPA_{\tau} (or BPP_{\tau} respectively) process X there is some (unspecified) normed BPP_{\tau} (or BPA_{\tau} respectively) process X such that X is bisimilar to X. Moreover, if the answer is positive then our algorithms also construct the process X. Simplified versions of the algorithms mentioned above for normed BPA and normed BPP are given too.

As an immediate (but important) consequence we also obtain the decidability of bisimilarity in the union of normed BPA_{\tau} and normed BPP_{\tau} processes.

Responsible contact: unixfimunicz