Extending Description Logics to Vague Knowledge in Medicine

This work introduces a concept language that is an extension of classical two-valued description logics to fuzzy logic. The new language allows to cope with vague concepts, e.g., more or less enlarged liver or very small kidney which are crucial notions in different medical application scenarios. To realize the extension to fuzzy logic, the classical logical notions of satisfiability, entailment and subsumption have to be modified appropriately. The main contribution of this paper are sound and complete methods for computing hierarchies between fuzzy concepts as well as processing queries in the new fuzzy concept language. Furthermore, we give an introduction to a concrete medical application that makes use of the fuzzy concept formalism.