Description Logics Description Logics Description logics are languages tailored for expressing knowledge about concepts and concept hierarchies. They are usually given a Tarski style declarative semantics, which allows them to be seen as sub-languages of predicate logic. Concepts can be considered as unary predicates which are interpreted as sets of individuals whereas roles are binary predicates which are interpreted as binary relations between individuals. The main reasoning tasks are classification and subsumption checking.
Subsumption represents the is-a relation.
A whole family of knowledge representation systems have been built using these languages and for most of them complexity results for the subsumption algorithm are known. Description logic systems have been used for building a variety of applications including software management systems, planning systems, configuration systems, and natural language understanding. My interests in description logics are particularly related related to adding defaults to description logics, adding facilities for reasoning with part-of and composite objects to description logics, and using description logics in applications, in conjunction with other systems.