| Eleni Tsalapati, Giorgos Stoilos, Giorgos Stamou, and George Koletsos |
| Query Rewriting Under Ontology Contraction |
| In Proceedings of the 6th International Conference on Web Reasoning and Rule Systems (RR2012), Vienna, p. 172-187, 10-12 September 2012. |
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ABSTRACT
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| Conjunctive query (CQ) answering is a key reasoning service for ontology-based data access. One of the most prominent approaches to conjunctive query answering is query rewriting where a wide variety of systems has been proposed the last years. All of them accept as input a fixed CQ q and ontology O and produce a rewriting for q,O . However, in many real world applications ontologies are very often dynamic—that is, new axioms can be added or existing ones removed frequently. In this paper we study the problem of computing a rewriting for a CQ over an ontology that has been contracted (i.e., some of its axioms have been removed) given a rewriting for the input CQ and ontology. Our goal is to compute a rewriting directly from the input rewriting and avoid computing one from scratch. We study the problem theoretically and provide sufficient conditions under which this process is possible. Moreover, we present a practical algorithm which we implemented and evaluated against other state-of-the-art systems obtaining encouraging results. Finally, axiom removal can also be relevant to ontology design. For each test ontology we study how much the removal of an axiom affects the size of the rewriting and the performance of systems. If the removal of a single axiom causes a significant decrease either in the size or in the computation time then this part of the ontology can be re-modelled.
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| 30 September, 2012 |
| Eleni Tsalapati, Giorgos Stoilos, Giorgos Stamou, and George Koletsos, "Query Rewriting Under Ontology Contraction", In Proceedings of the 6th International Conference on Web Reasoning and Rule Systems (RR2012), Vienna, p. 172-187, 10-12 September 2012. |
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