Prototypical reasoning with low complexity Description Logics: preliminary results

We present an extension EL+⊥T of the description logic EL+⊥ for reasoning about prototypical properties and inheritance with exceptions. EL+⊥T is obtained by adding to EL+⊥ a typicality operator T, which is intended to select the “typical” instances of a concept. In EL+⊥T knowledge bases may contain inclusions of the form “T(C) is subsumed by P”, expressing that typical C-members have the property P. We show that the problem of entailment in EL+⊥T is in co-NP.