Reasoning about Typicality in Low Complexity DLs: The Logics EL⊥Tmin and DL-Litec Tmin
We propose a nonmonotonic extension of low complexity Description Logics EL⊥ and DL-Litecore for reasoning about typicality and defeasible properties. The resulting logics are called EL⊥Tmin and DL-LitecTmin. Concerning DL-LitecTmin, we prove that entailment is in Πp2. With regard to EL⊥Tmin, we first show that entailment remains EXPTIME-hard. Next we consider the known fragment of Left Local EL⊥Tmin and we prove that the complexity of entailment drops to Πp2