Exploiting navigation capabilities in hypertext/hypermedia

Hypertext/hypermedia (HT/HM) applications need careful design. We outline a hypertext design methodology that leads to a consistent design of the nodes' structure, and makes it possible to model the different kinds of links that can exist among the nodes. The key concept is the formalization of two different spaces that the user can navigate across: the data space and the concept space. In particular, the introduction of the "concept space" permits an effective modelling of the intensional links. The user can navigate across both spaces, and move from one to another. The availability of these two spaces avoids overloading the nodes with too many intensional links, and helps to supply the hypertext with rich associative mechanisms, thus exploiting the potential of the basic hypertext philosophy. Particular attention is given to the representation of the navigational aspects; they are made evident to the user by means of a map of links, based on the concept of affinity between the nodes. Finally, we discuss some general implementation aspects, and point out the desirability of offering the user multiple and interchangeable interaction paradigms.