On Semantics and Correctness of Reactive Rule-Based Programs

The rule-based paradigm for knowledge representation appears in many disguises within computer science. In this paper we address special issues which arise when the rule-based programming paradigm is employed in the development of reactive systems. We begin by presenting a rule-based language RL which has emerged while developing intelligent cruise control systems. We de ne a desired declarative semantics and correctness criteria for rule-based programs which respect causality, synchrony assumption and desired determinism. Two alternative approaches are proposed to analyze RL programs. Both approaches build upon static checks of a rule-based program. In the rst approach we accept programs which are correct with respect to a constructive semantics while in the second approach, a strati cation check is imposed. The combination of rules and reactive behaviour, together with a formal analysis of this behaviour is the main contribution of our work.