Complexity of Approximate Query Answering under Inconsistency in Datalog+⁄−
Thomas Lukasiewicz‚ Enrico Malizia and Cristian Molinaro
Several semantics have been proposed to query inconsistent ontological knowledge bases, including the intersection of repairs and the intersection of closed repairs as two approximate inconsistency-tolerant semantics. In this paper, we analyze the complexity of conjunctive query answering under these two semantics for a wide range of Datalog+⁄− languages. We consider both the standard setting, where errors may only be in the database, and the generalized setting, where also the rules of a Datalog+⁄− knowledge base may be erroneous.