Temporal reasoning in a meta constraint logic programming architecture

Abstract

Constraint Logic Programming (CLP) is a powerful programming paradigm combining the advantages of Logic Programming and the efficiency of constraint solving. However, CLP presents some limitations in dealing with temporal reasoning. First, it uses an "arc consistency" propagation algorithm which cannot be changed by the user and it is too weak in many temporal frameworks. Second, CLP is not able to deal with qualitative temporal constraints. In this paper, we show how to overcome these limitations. In particular, we present a way of performing a path-consistency check without changing the propagation algorithm of the constraint solver. In addition, we show how to integrate qualitative and quantitative temporal reasoning by using a two module meta CLP architecture. Each module is a finite domain constraint solver (CLP(FD)). The object system (extended with the path-consistency algorithm) performs quantitative reasoning, while the meta-level reasons on constraints of the underlying system thus performing qualitative reasoning. In this way, we can benefit of the efficiency of the constraint handling mechanism of CLP and the modularity, flexibility and scalability of meta-architectures.