Polynomial Datalog Rewritings for Expressive Description Logics with Closed Predicates

Shqiponja Ahmetaj, Magdalena Ortiz, Mantas Simkus

Abstract: We consider instance queries mediated by an ontology expressed in the expressive DL ALCHIO with closed predicates. We observe that such queries are non-monotonic and cannot be expressed in monotonic variants of DATALOG, but a polynomial time translation into disjunctive DATALOG extended with negation as failure is feasible. If no closed predicates are present-in the case of classical instance checking in ALCHIO-our translation yields a positive disjunctive DATALOG program of polynomial size. To the best of our knowledge, this is the first polynomial time translation of an expressive (non-Horn) DL into disjunctive DATALOG.