Prototypical Reasoning with Low Complexity Description Logics: Preliminary Results

Abstract

We present an extension $\mathcal{EL}^{+^\bot}{\bf {\rm T}}$ of the description logic $\mathcal{EL}^{+^\bot}$ for reasoning about prototypical properties and inheritance with exceptions. $\mathcal{EL}^{+^\bot}{\bf {\rm T}}$ is obtained by adding to $\mathcal{EL}^{+^\bot}$ a typicality operator T, which is intended to select the “typical” instances of a concept. In $\mathcal{EL}^{+^\bot}{\bf {\rm T}}$ 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 $\mathcal{EL}^{+^\bot}{\bf {\rm T}}$ is in co-NP.