Specification of Complex Systems with Definite Clause Grammar

A clean and concise logical specification of complex reactive systems with Definite Clause Grammar (DCG) is given. The mathematical formalism of the visual language is based on a hierarchical state machine model. Progressing from parsing to code generation involves tree manipulation, for which Prolog is particularly well suited. The use of free logic variables in partially instantiated terms allows composite states of complex systems to be represented concisely. The use of anonymous variables further allows our hierarchical model to have different levels of abstraction of details.

Through syntax-directed translation, each state transition is mapped to a DCG rule. The intermediate code generated is a set of DCG rules. The well-known correspondence between grammar rule and Prolog clause allows the use of a homogeneous framework. As a result, a rigorous mathematical formalism of a visual specification language is mapped to a logical implementation.