The DReW System for Nonmonotonic DL-Programs

Nonmonotonic DL-programs provide a loose integration of Description Logic (DL) ontologies and Logic Programming (LP) rules with negation, where a rule engine can query an ontology with a native DL reasoner. However, in most systems for DL-programs, the overhead of an external DL reasoner might be considerable. Datalog-rewritable DL ontologies, such as most fragments of OWL 2 RL, OWL 2 EL, and OWL 2 QL, can be rewritten to Datalog programs, so that DL-programs can be reduced to Datalog¬, i.e, Datalog with negation, under both well-founded and answer set semantics. We developed the reasoner DReW that uses the Datalog-rewriting technique. In addition to DL-programs, DReW can also answer conjunctive queries under DL-safeness conditions over Datalog-rewritable ontologies, as well as reason on terminological default logics over such ontologies.