Answer sets for consistent query answering ininconsistent databases

Abstract

A relational database is inconsistent if it does notsatisfy a given set of integrity constraints. Nevertheless, it islikely that most of the data in it is consistent with theconstraints. In this paper we apply logic programming based onanswer sets to the problem of retrieving consistent information froma possibly inconsistent database. Since consistent informationpersists from the original database to every of its minimal repairs,the approach is based on a specification of database repairs usingdisjunctive logic programs with exceptions,whose answer set semantics can be represented and computed bysystems that implement stable model semantics. These programs allowus to declare persistence by default of data from the originalinstance to the repairs; and changes to restore consistency, byexceptions. We concentrate mainly on logic programs for binaryintegrity constraints, among which we find most of the integrityconstraints found in practice.