Section: New Results

Ontology networks

Dealing with the semantic web, we are interested in ontology networks, i.e., sets of distributed ontologies that have to work together. One way for these systems to interact consists of exchanging queries and answers. For that reason, we pay particular attention to query systems.

Querying the semantic web is mainly done through the sparql language or its extensions through paths and entailment regimes [14] . Query containment is the problem of deciding if the answers to a query are included in those of another query for any queried data sources. This problem is very important for query optimisation purposes. In the SPARQL context, it can be equally useful for distributing federated queries or for implementing schema-based access control. In order to experimentally assess implementation strengths and limitations, we provided a first SPARQL containment test benchmark. We studied the query demographics on DBPedia logs to design benchmarks for relevant query containment solvers. We tested available solvers on their domain of applicability on three different benchmark suites [6] and found that (i) tested solutions are overall functionally correct, (ii) in spite of its complexity, SPARQL query containment is practicable for acyclic queries, (iii) state-of-the-art solvers are at an early stage both in terms of capabilities and implementation.

This work has been developed in collaboration with the Tyrex team and within the PhD thesis of Melisachew Wudage Chekol now in the Orpailleur team. The benchmarks, results and software are available at http://sparql-qc-bench.inrialpes.fr .