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Appendix II:
The Integrated Hypertext

A hypertext system was deemed the most appropriate computational infrastructure to present knowledge resources offered to the learner. In traditional text processing systems, a document is no more than a sequence of character strings which are stored and retrieved in a strictly linear fashion. The essential innovation of hypertext consists in abandoning this linearity constraint. The hypertext approach views a document as a set of text chunks corresponding to conceptual nodes in a database; a system of machine-supported links between nodes and chunks allows interactive branching within and between documents. Hypertext systems exploit more recent computer interfacing technology, particularly window management and graphics tools. Conceptual entities are displayed as windows of text which may contain any number of icons or buttons representing links to other nodes. The user can navigate freely around the hyperdocument by clicking on any of these graphics pointers.

II.1. Design

While commercial hypertext shells are available, we have implemented our own hypertext system for several reasons:

The hypertext we developed does not provide new facilities that do not exist on similar systems, its originality is to have a degree of integration with the other system components:

The underlying position did not only focus on how learners seek for information but also on why they need information. More than a simple technical issue, the degree of integration measures the extent to which the need for information comes from other activities performed within the learning environment.

II.2. Implementation

The hypertext subsystem is implemented as a class of objects called hypernodes. Each hypernode contains a title and a chunk of text with embedded formatting commands. Moreover, each node has an associated list of keywords summarizing the semantic content of its main text. These keywords serve as the basis of an indexing facility.

A hypertext is written by using a small subset of Latex commands which then have to be compiled in order to be used on-line. We included book structure commands (chapter, section,...). This way an author can combine the advantages of linear and `web' text. A special graphic browser allows to display the linear structure of a hypertext and to jump to a section. Because of the use of a Latex, hypertext documents can be printed easily. For instance, the user manual of Memolab is available both as an on-line hypertext or as a printed document.

The following facilities for `navigation' have been implemented:

Figure 13: A hypertext from MEMOLAB and the `search' facility.

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