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Ontologies for Knowledge Sharing

To support the sharing and reuse of formally represented knowledge among AI systems, it is useful to define the common vocabulary in which shared knowledge is represented. A specification of a representational vocabulary for a shared domain of discourse -- definitions of classes, relations, functions, and other objects -- is called an ontology.


  • A. Farquhar, R. Fikes, & J. Rice. The Ontolingua Server: A Tool for Collaborative Ontology Construction. Knowledge Systems Laboratory, KSL-96-26, September 1996. Reusable ontologies are becoming increasingly important for tasks such as information integration, knowledge-level interoperation, and knowledge-base development. We have developed a set of tools and services to support the process of achieving consensus on common shared ontologies by geographically distributed groups. These tools make use of the world-wide web to enable wide access and provide users with the ability to pub-lish, browse, create, and edit ontologies stored on an ontology server. Users can quickly assemble a new ontology from a library of modules. We discuss how our system was constructed, how it exploits existing protocols and browsing tools, and our experience supporting hundreds of users. We describe applications using our tools to achieve con-sensus on ontologies and to integrate information. The Ontolingua Server may be accessed through the URL http://ontolingua.stanford.edu/.

  • A Guided Tour to Developing Ontologies Using Ontolingua -- for people who would like an introduction both to developing ontologies and to using the Ontolingua Ontology Editor provided by the Stanford KSL Network Services for creating and modifying ontologies.

  • Stanford KSL Network Services -- including an ontology editor.


  • the Stanford Knowledge Sharing paper repository
  • What is an Ontology? by Tom Gruber.
  • Toward principles for the design of ontologies used for knowledge sharing, T. R. Gruber, in Formal Ontology in Conceptual Analysis and Knowledge Representation, Nicola Guarino and Roberto Poli, editors, Kluwer Academic, in preparation. Original paper presented at the International Workshop on Formal Ontology, March 1993. Stanford Knowledge Systems Laboratory Report KSL-93-04.

    Recent work in Artificial Intelligence is exploring the use of formal ontologies as a way of specifying content-specific agreements for the sharing and reuse of knowledge among software entities. We take an engineering perspective on the development of such ontologies. Formal ontologies are viewed as designed artifacts, formulated for specific purposes and evaluated against objective design criteria. We describe the role of ontologies in supporting knowledge sharing activities, and then present a set of criteria to guide the development of ontologies for these purposes. We show how these criteria are applied in case studies from the design of ontologies for engineering mathematics and bibliographic data. The rationale for selected design decisions in these ontologies is presented. Alternative representations are compared and evaluated against the general criteria. In particular, the case studies illustrate the notions of encoding bias and ontological overcommitment and suggest ways to avoid them in the design of ontologies for knowledge sharing. [an error occurred while processing this directive]