Inconsistency−Tolerant Query Rewriting for Linear Datalog+⁄−

Abstract

Inconsistency management in knowledge bases is an important problem that has been studied for a long time. During the recent years, additional interest in this topic has been sparked with the advent of the Semantic Web, which has made this problem even more relevant, since inconsistencies are very likely to occur in open environments such as the Web. Inconsistency-tolerant semantics to query answering have therefore become of special interest for representation and reasoning formalisms for the Semantic Web. Datalog+/- is a family of ontology languages that is in particular useful for representing and reasoning over lightweight ontologies in the Semantic Web. In this paper, we focus on inconsistency-tolerant query answering under the intersection semantics in linear Datalog+/-, a sublanguage of Datalog+/- that generalizes the DL-Lite family of tractable description logics (DLs). In particular, we show that query answering in linear Datalog+/- is first-order rewritable under this inconsistency-tolerant semantics, and therefore very efficiently computable in the data complexity.