Tech Report CS-91-26

RelType: Relaxed Typing for Intelligent Hypermedia Representations

Dilip K. Barman

April 1991


RelType is a flexible typing scheme, primarily for the links of a hypermedia system, that models hypertext as an object-oriented knowledge representation (KR) medium. The typing is non-intrusive in allowing but not enforcing hypertext link (and node) type specifications. Users continue to have complete linking flexibility, but may choose to use one of a small number of predefined types with associated semantics (e.g., subsumption, explanation) or to define their own types. The ensuing structure, akin to a semantic net, is type checked and specified semantic actions executed. The structure is semantically as rich as the user wished and could, at least partially, support tractable inference. Tools also allow a RelType system to evolve semantically in a manner reflecting actual usage. Taxonomic and assertional components capture domain knowledge. An object-oriented view supports knowledge acquisition and eases extensibility, particularly through use of linked templates. RelType provides the flexibility of hypertext, combined with some of the representational power of term classification KR systems, in an efficient and usable manner.

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