From Classical to Consistent Query Answering under Existential Rules
Thomas Lukasiewicz‚ Maria Vanina Martinez‚ Andreas Pieris and Gerardo I. Simari
Querying inconsistent ontologies is an intriguing new problem that gave rise to a flourishing research activity in the description logic (DL) community. The computational complexity of consistent query answering under the main DLs is rather well understood; however, little is known about existential rules. The goal of the current work is to perform an in-depth analysis of the complexity of consistent query answering under the main decidable classes of existential rules enriched with negative constraints. Our investigation focuses on the standard inconsistency-tolerant semantics, namely, the AR semantics. We establish generic complexity results, which demonstrate the tight connection between classical and consistent query answering. These results allow us to obtain in a uniform way a relatively complete picture of the complexity of our problem.