Practical update management in ontology-based data access

Ontology-based Data Access (OBDA) is gaining importance both scientifically and practically. However, little attention has been paid so far to the problem of updating OBDA systems. This is an essential issue if we want to be able to cope with modifications of data both at the ontology and at the source level, while maintaining the independence of the data sources. In this paper, we propose mechanisms to properly handle updates in this context. We show that updating data both at the ontology and source level is first-order rewritable. We also provide a practical implementation of such updating mechanisms based on non-recursive Datalog.Peer ReviewedPostprint (author's final draft

On the Satisfiability of Quasi-Classical Description Logics

Though quasi-classical description logic (QCDL) can tolerate the inconsistency of description logic in reasoning, a knowledge base in QCDL possibly has no model. In this paper, we investigate the satisfiability of QCDL, namely, QC-coherency and QC-consistency and develop a tableau calculus, as a formal proof, to determine whether a knowledge base in QCDL is QC-consistent. To do so, we repair the standard tableau for DL by introducing several new expansion rules and defining a new closeness condition. Finally, we prove that this calculus is sound and complete. Based on this calculus, we implement an OWL paraconsistent reasoner called QC-OWL. Preliminary experiments show that QC-OWL is highly efficient in checking QC-consistency

Query Rewriting for Inconsistent DL-Lite Ontologies

Abstract. In this paper we study the problem of obtaining meaningful answers to queries posed over inconsistent DL-Lite ontologies. We consider different variants of inconsistency-tolerant semantics and show that for some of such variants answering unions of conjunctive queries (UCQs) is first-order (FOL) rewritable, i.e., it can be reduced to standard evaluation of a FOL/SQL query over a database. Since FOL-rewritability of query answering for UCQs over consistent ontologies under first-order logic semantics is one of the distinguishing features of DL-Lite, in this paper we actually identify some settings in which such property is preserved also under inconsistency-tolerant semantics. We therefore show that in such settings inconsistency-tolerant query answering has the same computational complexity of standard query answering and that it can rely on well-established relational database technology, as under standard DL semantics.