A Library of Medical Ontologies

This paper describes an initial version of a library of sharable and reusable medical ontological theories, organized according to a proposed classiication of ontologies. 1 1 What is an ontology? The term ontology arises from the philosophical tradition, within which it's typically polysemous Poli, 1993]; that is, it presents multiple meanings. However, ontology can be generally deened as the doctrine of being or the science of objects (`real' objects as well as abstract, mental or ideal objects). While classical ontology is the result of \the intuitive study of the fundamental properties, modes, and aspects of being, or of entities in general", formal ontology is \the result of combining the intuitive, informal method of classical ontology with the formal, mathematical method of modern symbolic logic" Burkhardt & Smith, eds., 1991]. There are analogies between the outlined philosophical notion of ontology and the knowledge engineering notion of conceptualization, as deened e.g. in Genesereth & Nils-son, 1987]. We can summarize such a deenition as follows: The formalization of knowledge in declarative form begins with a conceptu-alization, which includes the objects (concrete or abstract, primitive or composite , `real' or ctional) presumed or hypothesized to exist in some area of interest and their assumed interrelationships (functions or relations). Thus, within the context of knowledge engineering, an ontology can be viewed as an explicit speciication of a conceptualization, that is as a set of deenitions, which associate a term (the name of the deened entity) with axioms that constrain its use and relate it to other terms Gruber, 1993a; Gruber, 1993b]. According to the formal, logic-based language we adopted to write ontologies, Ontolin-gua Gruber, 1992], we discern four basic kinds of deenitions: classes, relations, functions and class instances. Deenitions can be grouped into theories, collections of deenitions that are consistent and somehow related. A logical theory is a set of axioms, an Ontolingua theory is a named set of deenitions expressed through axioms. 1 The paper is not yet nished, but the library description is quasi deenitive. Theories can include other theories, which means that all the deenitions in the included theories are also available in the including theory. Operationally speaking, inclusion realizes , at the including theory level, the union of the sets of deenitions relative to all of the theories. Hence, the involved deenitions must be logically consistent, and incompatible deenitions for the same name will not be allowed. In general, it can …