Computer Aided Transformation of Z into Prolog

Abstract

A strategy for the rapid prototyping of Z specifications is described. The semantics of Z are captured in a library of Prolog rules based on a standard specification of the language constructs. Each Z schema is translated directly into a Prolog rule which is then transformed for efficiency. A classical generate-and-test form is used to mirror the structure of a schema; goals resulting from the schema variable declarations are used to generate candidate instantiations, and goals resulting from the schema predicate part are used to test the instantiations for required properties. The incompleteness of the Prolog search strategy limits the approach to the use of finite sets. Negation by failure places limitations on the kinds of transformation that can be applied. A set of tools is being developed to explore the potential of this approach for the animation of Z specifications. These tools include a Z-to-Prolog translator, a transformation aid, and an animator. Initial experiments with the transformation tool suggest that the approach can offer more than simple animation; execution of the Prolog can also be used to check logical consistency and non-determinism.