Distributed Explicit State Model Checking of Deadlock Freedom

This paper presents a practical method and associated tool for verifying deadlock freedom properties in guarded command systems. Such properties are expressed in CTL as AGEF q where q is a set of quiescent states. We require the user to provide transitions of the system that are “helpful” in reaching quiescent states. The distributed search constructs a path consisting of helpful transitions from each reachable state to a state that is either quiescent or is known to have a path to a quiescent state. We extended the PReach model-checker with these algorithms. Performance measurements on both academic and industrial large-scale models shows that the overhead of checking deadlock-freedom compared with state-space enumeration alone is small.