Towards Defeasible SROIQ

We present a decidable extension of the Description Logic SROIQ that supports defeasible reasoning in the KLM tradition, and extends it through the introduction of defeasible roles. The semantics of the resulting DL dSROIQ extends the classical semantics with a parameterised preference order on binary relations in a domain of interpretation. This allows for the use of defeasible roles in complex concepts, as well as in defeasible concept and role subsumption, and in defeasible role assertions. Reasoning over dSROIQ ontologies is made possible by a translation of entailment to concept satisfiability relative to an RBox only. A tableau algorithm then decides on consistency of dSROIQ-concepts in the preferential semantics.