University of Brasilia
One of the main applications of ontologies in computer science is in data access, where an ontology formalizes conceptual information about data that is stored in one or multiple data sources, and this information is used to derive answers to queries over such sources. Conjunctive Queries (CQ) are fundamental for accessing Description Logic (DL) knowledge bases. The authors study CQ answering in (extensions of) the DL EL, which is popular for large-scale ontologies and underlies the designated OWL2-EL profile of OWL2. Their main contribution is a novel approach to CQ answering that enables the use of standard relational database systems as the basis for query execution. They evaluate their approach using the IBM DB2 system, with encouraging results.