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T. Eiter, M. Fink, D. Stepanova:
"Computing Repairs of Inconsistent DL-Programs over EL Ontologies";
Journal of Artificial Intelligence Research, 56 (2016), S. 463 - 515.

Description Logic (DL) ontologies and non-monotonic rules are two prominent Knowledge representation (KR) formalisms with complementary features that are essential for various applications. Non-monotonic Description Logic (DL) programs combine these formalisms thus providing support for rule-based reasoning on top of DL ontologies using a well-defined query interface represented by so-called DL-atoms. Unfortunately, interaction of the rules and the ontology may incur inconsistencies such that a DL-program lacs answer sets (i.e. models), and thus yields no informations. This issue is addressed by recently defined repair answer sets, for computing which an effective practical algorithm was proposed fo DL-Lite ontologies that reduces a repair computation to constraint matching based on so-called support sets. However, the algorithm exploits particular features of DL-Lite and can not be readily applied to repairing DL-programs over other prominent DLs like EL. Compared to DL-Lite, in EL support sets may neither be small nor only few support sets might exist, and completeness of the algorithm may need to be given up when the support information is bounded. we thus provide an approach for computing repairs for DL-programs over EL ontologies based on partial (incomplete)support families. The latter are constructed using datalog query rewriting techniques as well as ontology approximation based on logical difference between EL terminologies. We show how the maximal size and number of support sets for a given DL-atom can be estimated by analyzing the properties of a support hypergraph, which characterizes relevant set of TBox axioms needed for query derivation. We present a declarative implementation of the repair approach and experimentally evaluate it on a set of benchmark problems; the promising results witness practical feesibiliby of our repair approach.

Ontologies, Description Logics, Knowledge Representation, DL-Lite, DL-programs, EL ontologies

http://publik.tuwien.ac.at/files/publik_256527.pdf

Projektleitung Thomas Eiter:
Answer Set Programmierung für das Semant