Compositional Nonblocking Verification Using Annotated Automata

This paper proposes to enhance compositional verification of the nonblocking property of discrete event systems by introducing annotated automata. Annotations store nondeterministic branching information, which would otherwise be stored in extra states and transitions. This more succinct representation makes it easier to simplify automata and enables new efficient means of abstraction, further reducing the size of automata to be composed and thus the size of the synchronous product state space encountered in verification. The abstractions proposed are of polynomial complexity, and they have been successfully applied for nonblocking verification of the same set of large-scale industrial examples as used in related work.