DESCRIPTION LOGICS FOR RELATIVE TERMINOLOGIES OR WHY THE BIGGEST CITY IS NOT A BIG THING

Abstract. Context-sensitivity has been for long a subject of study in linguistics, logic and computer science. Recently the problem of representing and reasoning with con-textual knowledge has been brought up in the research on the Semantic Web. In this paper we introduce a conservative extension to Description Logic, the formalism underlying Web Ontology Languages, supporting representation of ontologies con-taining relative terms, such as ‘big ’ or ‘tall’, whose meaning depends on the selection of comparison class (context). The solution rests on introduction of modal-like op-erators in the language and an additional modal dimension in the semantics, which is built upon the standard object dimension of the Description Logic languages and whose states correspond to selected subsets of the object domain. We present the syntax and semantics of the extended language and elaborate on its representational and computational features. 1