Terminological Logics with Modal Operators

Terminological knowledge representation formalisms can be used to represent objective, time-independent facts about an application domain. Notions like belief, intentions, and t ime which are essential for the representation of mult i-agent environments can only be expressed in a very l imi ted way. For such not i ons, modal logics w i th possible worlds semantics provides a formal ly well-founded and wellinvestigated basis. This paper presents a framework for integrating modal operators into terminological knowledge representation languages. These operators can be used both inside of concept expressions and in front of terminological and assertional axioms. We introduce syntax and semantics of the extended language, and show that satisfiabil i ty of f inite sets of formulas is decidable, provided that all modal operators are interpreted in the basic logic K, and that the increasing domain assumption is used.