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Conference Proceeding

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Despite the success of the Web Ontology Language OWL, the development of expressive means for querying OWL knowledge bases is still an open issue. In this paper, we investigate how a very natural and desirable form of queries-namely conjunctive ones-can be used in conjunction with OWL such that one of the major design criteria of the latter-namely decidability-can be retained. More precisely, we show that querying the tractable fragment EL++ of OWL 1.1 is decidable. We also provide a complexity analysis and show that querying unrestricted EL++ is undecidable.


Presented at the 6th International Semantic Web Conference, Busan, Korea, November 11-15, 2007.

Attached is the unpublished, authors' version of this proceeding. The final, publisher's version can be found at