Unfoldings of Unbounded Petri Nets

Net unfoldings have attracted much attention as a powerful technique for combating state space explosion in model checking. The method has been applied to veriication of 1-safe ((nite) Petri nets, and more recently also to other classes of nite-state systems such as synchronous products of nite transition systems. We show how unfoldings can be extended to the context of innnite-state systems. More precisely, we apply unfoldings to get an eecient symbolic algorithm for checking safety properties of unbounded Petri nets. We demonstrate the advantages of our method by a number of experimental results.