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The ontological commitment of the medical ontology ON8.5, produced by the ONIONS methodology, is explained. ONIONS provides a feasible procedure to integrate structured lexical repositories, and is based on semiology. The application of ONIONS to medicine is described as far as commitment choices and reuse issues are concerned. A-posteriori, a compatible formal characterization of the commitment of meta-level categories is shown to be obtainable by means of Guarino's ontology.
We introduce ONIONS (ONtologic Integration Of Naïve Sources), a methodology for coping with the knowledge integration problem. We describe the ONIONS theory of meaning, its procedure of knowledge integration, and some results of its application to the medical domain, including a description of the top model of ON8.5 ontology with an explanation of its commitment.
ONIONS is based on the belief that many ontologic problems of knowledge acquisition come from the need for sources of motivated knowledge, which are eventually heterogeneous in their conceptualizations. Once such sources are taken into account, immediately the knowledge integration problem arises. ONIONS treats it in an explicit and rational way, i.e., by assuming that relevant knowledge in a domain could be extracted by understanding and generalizing the conceptualizations inherent in the lexical repositories of a domain.
Fig.1: The onion metaphor: a conceptualization can be described as a linkage of theories to a complex concept.
On this premise, we propose a layered approach to ontological engineering:
Such definitions are partially derived from several discussions about differences in the intended meaning of ontology [Cocchiarella, 1991; Gruber, 1993; Guarino, 1995; Gangemi&al, 1996]. The following is a further schematization:
In [Gangemi&al, 1995a; Steve&al, 1996; Gangemi&al, 1996] we introduced ONIONS, a methodology for aiding the creation of a domain formal ontology from the integration of distinct, authoritative taxonomic knowledge repositories. ONIONS allows to perform ontological analyses with a "built-in" solution to the knowledge integration problem. The integration approach of ONIONS is suited to naturally introduce an ontological commitment for the theories derived through its application.
The main application of ONIONS has been made in the domain of medicine. The resulting medical ontology is currently ON8.5 (in [Gangemi&al, 1996] an appendix is presented which contains the formal model of ON8.5 in an order-sorted-logic.
In par. 1. we describe the theory of meaning underlying ONIONS; in par. 2., the ontology acquisition methodology; in par. 3., some description of ON8.5 top-level; in par. 4., some concept structuring issues: the decision tools for tagging concepts by MLC, and some mapping of our MLC to the ontology of MLC introduced by Guarino [Guarino, 1992; Guarino&al, 1994; Guarino&Boldrin, 1993].