A Description Logic for Vague Knowledge

This work introduces the concept language ALC(FM) which is an extension of ALC to many-valued logics. ALC(FM) allows to express vague concepts, e.g. `more or less enlarged'' or `very small''. To realize this extension to many-valued logics, the classical notions of satisfiability and subsumption had to be modified appropriately. For example, ALC(FM)-concepts are no longer either satisfiable or unsatisfiable, but they are satisfiable to a certain degree. The main contribution of this paper is a sound and complete method for computing the degree of subsumption between two ALC(FM)-concepts.