Constrained Multiset Rewriting

We investigate model checking of a computation model called Constrained Multiset Rewriting Systems (CMRS). A CMRS operates on configurations which are multisets of monadic predicate symbols, each with an argument ranging over the natural numbers. The transition relation is defined by a finite set of rewriting rules which are conditioned by simple inequalities on variables and constants. This model is able to specify systems with an arbitrary number of components where the internal state of a component may contain values ranging over the natural numbers. We show that CMRS are strictly more powerful than two existing related models namely that of Petri nets and relational automata. We prove decidability of the coverability problem, and undecidability of repeated reachability and configuration reachability for CMRS. Furthermore, we show that decidability of coverability does not extend to some natural extensions of the model, including the case where the predicates are dyadic. We report on using a prototype implementation to verify parameterized versions of a mutual exclusion and an authentication protocol.