Towards Very Large Ontologies for Medical Language Processing
Udo Hahn (Text Knowledge Engineering Lab, Freiburg University, Werthmannplatz 1 D-79098 Freiburg, Germany)
Stefan Schulz (Text Knowledge Engineering Lab, Freiburg University, Werthmannplatz 1 D-79098 Freiburg, Germany)
We describe an ontology engineering methodology by which conceptual knowledge is extracted from an informal medical thesaurus (UMLS) and automatically converted into a formal description logics system. Our approach consists of four steps: concept definitions are automatically generated from the UMLS source, integrity checking of taxonomic and partonomic hierarchies is performed by the terminological classifier, cycles and inconsistencies are eliminated, and incremental refinement of the evolving knowledge base is performed by a domain expert. We report on experiments with a knowledge base composed of 164,000 concepts and 76,000 relations.