INFINITY 2008 Normed Processes, Unique Decomposition, and Complexity of Bisimulation Equivalences

We propose a decision procedure for a general class of normed commutative process rewrite systems and their induced bisimulation equivalences. Our technique is inspired by the polynomial-time algorithm for strong bisimilarity on normed Basic Parallel Processes (BPP), developed by Hirshfeld, Jerrum and Moller. As part of our framework we present a generic unique decomposition result, which we obtain by building on a characterization by Luttik and van Oostrom. We apply our general technique to derive polynomialtime algorithms for strong bisimilarity on normed BPP with communication and for distributed bisimilarity on all BPP with communication. Moreover, our technique yields a PSPACE upper bound for weak and branching bisimilarity on totally normed BPP.