Compositional action system derivation using enforced properties

Action systems have been shown to be applicable for modelling and constructing both sequential and concurrent systems. This paper presents an approach to program construction where the concrete implementation is derived from its specification - via a series of small refinements - using incomplete proofs to motivate changes to the program. Formalisation of our approach is provided by enforced properties, which restrict the traces of a program to those that satisfy the enforced properties. The goal of the derivation is to refine a program with enforced properties to a program (with no enforced properties) whose code satisfies the enforced properties. An advantage of this approach is that the code in the earlier versions of the program need not be complete; incorrect execution of the program is avoided by including enforced properties in the specification. Enforced properties may be any temporal formula or relation, and hence we may reason about both safety and progress in a compositional setting