An object-oriented framework for knowledge representation based on fuzzy sets

In this article we describe the extensions of a data model developed in our department suitable for hypermedia information systems. These extensions are meant to support knowledge representation and uncertainty handling. Two levels of abstraction are introduced. The higher (concepts, relationships) aims at defining the framework in which the lower (hypermedia nodes and links) can be developed. It is important to stress that the model is capable of dealing with the uncertainty of the relationships. Methods from the fuzzy sets theory are adopted for reasoning based on these features. The model also supports contexts and means for inference based on the rules class. A sample application presents the model's potential in the tourist domain. The application consists of a hypermedia network regarding tourist aspects of Crete, a famous Greek resort. A set of rules is defined to answer a query involving fuzzy criteria.