Veri cation Based on Local States ?

Net unfoldings are a well-known partial order semantics for Petri nets. Here we show that they are well suited to act as models for branching-time logics interpreted on local states. Such local logics (in particular a distributed-calculus) can be used to express properties from the point of view of one component in a distributed system. Local logics often allow for more eecient veriication procedures because { in contrast to interleaving branching-time logics { they do not refer to the entire space of global states. We reduce veriication of local properties to standard model checking algorithms known for interleaving branching-time logics. The key is to extract a nite (usually small), local transition system bisimilar to the complete unfolding. The construction is based on the nite preex of a net unfolding deened by McMillan.