Download PDFOpen PDF in browserHybrid Unification in the Description Logic EL5 pages•Published: July 29, 2013AbstractUnification in Description Logics (DLs) has been proposed as an inferenceservice that can, for example, be used to detect redundancies in ontologies. For the DL EL, which is used to define several large biomedical ontologies, unification is NP-complete. However, the unification algorithms for EL developed until recently could not deal with ontologies containing general concept inclusions (GCIs). In a series of recent papers we have made some progress towards addressing this problem, but the ontologies the developed unification algorithms can deal with need to satisfy a certain cycle restriction. In the present paper, we follow a different approach. Instead of restricting the input ontologies, we generalize the notion of unifiers to so-called hybrid unifiers. Whereas classical unifiers can be viewed as acyclic TBoxes, hybrid unifiers are cyclic TBoxes, which are interpreted together with the ontology of the input using a hybrid semantics that combines fixpoint and declarative semantics. We show that hybrid unification in EL is NP-complete Keyphrases: description logic, np complete, unification In: Konstantin Korovin and Barbara Morawska (editors). UNIF 2013. 27th International Workshop on Unification, vol 19, pages 8-12.
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