Automating approximations in DL-Lite ontologies

As the avid keet blog reader or attendee to one of my ontology engineering courses may remember, I politely aired my frustration when one has an OWL 2 DL ontology that needs to be ‘slimmed’ to a DL-Lite (roughly: OWL 2 QL) one to make it useable for Ontology-Based Data Access (OBDA)—already since the experiment with the ontology/OBDA for disabilities [1]. This is a difficult and time-consuming exercise to do manually, especially when one has to go back and forward between the slimmed and expressive version of the ontology. Back in 2008, the difficulties were due both to a flaky Protégé 4.0-alpha and a mere syntactic approximation. Finally, things have improved and a preliminary semantic approximation is available [2] (and recently presented at AIMSA’10), which was developed by my colleagues at the KRDB Research centre.

Well, ok, only some aspects of the sound and complete approximations are addressed (more precisely: chains of existential role restrictions) and for DL-LiteA only, but they have been implemented already. The implementations are available in three forms: a Java API, a command line application suitable for batch approximations, and as a plug-in for Protégé 4.0. Note though, that the approximation algorithm is exponential, so with a large ontology it might take some time to simplify the expressive ontology. I did not test this myself yet, however, so if you have any comments or suggestions, please contact the authors of [2] directly. More is in the pipeline, and I am looking forward to more of such results—sure, this is with some self-interest: it will ease not only transparent, coordinated ontology management and development of ontology-driven information systems, but also facilitate implementation scenarios for rough ontologies [3].

References

[1] Keet, C.M., Alberts, R., Gerber, A., Chimamiwa, G. Enhancing web portals with Ontology-Based Data Access: the case study of South Africa’s Accessibility Portal for people with disabilities. Fifth International Workshop OWL: Experiences and Directions (OWLED’08). 26-27 Oct. 2008, Karlsruhe, Germany.

[2] Elena Botoeva, Diego Calvanese, and Mariano Rodriguez-Muro. Expressive Approximations in DL-Lite Ontologies. Proc. of the 14th Int. Conf. on Artificial Intelligence: Methodology, Systems, Applications (AIMSA’10). Sept 8-10, 2010, Varna, Bulgaria.

[3] Keet, C.M. Ontology engineering with rough concepts and instances17th International Conference on Knowledge Engineering and Knowledge Management (EKAW’10). 11-15 October 2010, Lisbon, Portugal. Springer LNAI 6317, 507-517.

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