Specifying & verifying concurrent systems using Z

Abstract

At present, few guidelines exist for applying the Z notation to concurrent systems, while existing approaches to proving properties of Z specifications of concurrent systems place emphasis on the use of additional formalisms such as temporal logic. This paper proposes a practical and rigorous approach to specifying and verifying concurrent systems using the Z notation alone. Guidelines are given for specifying common features of concurrent systems in Z. A simple lift controller systems is then specified. Finally, a formal proof method based on a simple (weak) fairness rule is presented and is illustrated by means of proofs of safety and liveness properties of the lift controller system.