They are usually given a Tarski style declarative semantics, which allows them to be seen as sub-languages of predicate logic. The basic building blocks are concepts, roles and individuals. Concepts describe the common properties of a collection of individuals and can be considered as unary predicates which are interpreted as sets of objects. Roles are interpreted as binary relations between objects. The main reasoning tasks are classification and satisfiability, subsumption and instance checking.
Subsumption represents the is-a relation.
Classification is the computation of a concept hierarchy based on subsumption. A whole family of knowledge representation systems have been built using these languages and for most of them complexity results for the main reasoning tasks are known. Description logic systems have been used for building a variety of applications including conceptual modeling, information integration, query mechanisms, view maintenance, software management systems, planning systems, configuration systems, and natural language understanding. Reference List which you can search To add a new entry, send a mail . Comments, suggestions, pointers to papers, systems and people are welcome.