Combining Formal Methods for the Development of Reactive Systems

Abstract

This article deals with the use of two verification approaches: theorem proving and model checking. We focus on the Event-B method by using its associated theorem proving tool (Click_n_Prove), and on the language TLA + by using its model checker TLC. By considering the limitation of the Event-B method to invariance properties, we propose to apply the language TLA + to verify liveness properties on a software behavior. We extend first the expressivity and the semantics of a B model (called temporal B model ) to deal with the specification of fairness and eventuality properties. Second, we give transformation rules from a temporal B model into a TLA + module. We present in particular, our prototype system called B2TLA + , that we have developed to support this transformation; then we can verify these properties thanks to the model checker TLC on finite state systems. For the verification of infinite-state systems, we propose the use of the predicate diagrams. We illustrate our approach on a case study of a parcel sorting system.