Answer Synthesis for CLP Programs with Negation

Rewrite techniques can be used to execute logic programs in order to avoid some drawbacks of classical Prolog resolution. Logic programs are represented as rewrite programs whose operational mechanism, inspired from Knuth-Bendix completion, allows to prune some unnecessary computations and ooers a synthesis ability which enables to represent innnite sets of answers as nite sets of formulas. We propose here a full extension of this approach to Constraint Logic Programming (CLP) with negation. Issued from rewrite techniques, a very powerful simpliication rule is deened, available in a more general context than strict instantiation. Thanks to this rule, solutions are obtained as a set of constrained rewrite rules with more expressive power than simple constraints used in a classical CLP framework. Thus, our mechanism, integrating both non symbolic constraints and negation, keeps the loop avoiding and synthesis properties. Furthermore, the system is proved sound and complete with regard to the standard CLP semantics.