Applying Discourse Theory to Aid Hypertext Navigation

We discuss ways of improving navigation facilities in hypertext systems, considering theoretical and implementation issues, from a natural language processing research perspective. The key claim is that certain ideas from the theory of discourse structure can be exploited to improve the context-sensitivity of navigation facilities. In particular, (i) after a node is reached by a jump, links to other nodes can by dynamically suppressed where these are rendered irrelevant by the user's mode of arrival; and (ii) at any point after a jump (or sequence of jumps), the user can easily return to a limited set of structurally accessible nodes. The approach therefore combines certain advantages of navigation based on document structure with those based on individual interaction histories. The ideas have been tested by altering the implementation of Info, the hypertextual help system built into the Emacs text editor, which runs on Unix, Macintosh and pc systems. Evaluation studies are currently being planned, and we see further potential for exploiting notions from discourse structure to inform the design of navigation aids.