A framework for compositional nonblocking verification of extended finite-state machines

This paper presents a framework for compositional nonblocking verification of discrete event systems modelled as extended finite-state machines (EFSM). Previous results are improved to consider general conflict-equivalence based abstractions of EFSMs communicating both via shared variables and events. Performance issues resulting from the conversion of EFSM systems to finite-state machine systems are avoided by operating directly on EFSMs, deferring the unfolding of variables into state machines as long as possible. Several additional methods to abstract EFSMs and remove events are also presented. The proposed algorithm has been implemented in the discrete event systems tool Supremica, and the paper presents experimental results for several large EFSM models that can be verified faster than by previously used methods