A Unifying Framework for Abductive and Constraint Logic Programming

by Gerhard Wetzel 
Brooklyn College, New York, USA 

Abstract

This paper, which is based on [We97], presents a unifying framework for the areas of Abductive 
Logic Programming (ALP), Constraint Logic Programming (CLP) and Semantic Query Optimiza-
tion (SQO). Links between these areas are pointed out and used to motivate an extension of normal 
LP by integrity constraints. Moreover, LP if clauses are replaced by if-and-only-if definitions with 
disjunctions in their bodies.

A proof procedure, consisting of four core operations, is defined for the new framework. It simpli-
fies previously proposed abductive proof procedures [Fu96, DeDS97] and generalizes them so that 
they are no longer specialized on abduction. Some possible extensions of the core operations are 
also presented.

Traditional problems from LP, ALP, CLP, and SQO as well as interdisciplinary AI problems con-
stitute possible applications of the new framework. Some examples are given to illustrate the 
bene,ts of appplying the unified framework.