The latest ontology languages can be translated into a description logic (DL), thus providing them with a formal semantics and associated reasoning procedures. We introduce the ordered description logic OSHOQ(D) as a simple decidable extension of SHOQ(D) that supports the direct definition of a preference order on defeasible axioms, thus allowing for a succinct and intuitive expression of defeasible ontologies, containing e.g. exceptions for certain axioms.

We demonstrate the usefulness of OSHOQ(D) for solving inconsistencies that may appear e.g. when merging existing ontologies. We present an algorithm that, based on concrete examples of facts that should be true, produces minimal preference orderings on the axioms, in order to make an otherwise inconsistent knowledge base consistent.