Transformation Rules for Locally Stratified Constraint Logic Programs

TL;DR

This paper introduces a set of transformation rules for locally stratified constraint logic programs with negation, ensuring the preservation of their unique perfect model during transformations.

Contribution

It extends existing transformation rules by including new rules for unfolding clauses with negative literals, specifically tailored for locally stratified constraint logic programs.

Findings

Transformation rules preserve the perfect model under certain conditions

Rules extend previous logic and constraint logic program transformations

Includes a novel rule for unfolding with negative literals

Abstract

We propose a set of transformation rules for constraint logic programs with negation. We assume that every program is locally stratified and, thus, it has a unique perfect model. We give sufficient conditions which ensure that the proposed set of transformation rules preserves the perfect model of the programs. Our rules extend in some respects the rules for logic programs and constraint logic programs already considered in the literature and, in particular, they include a rule for unfolding a clause with respect to a negative literal.