Programming Research Group Technical Monograph PRG-97

Gregory D Abowd

DPhil thesis October 1991, 232 pages, ISBN 0-902928-75-9

This thesis provides a constructive application of formal methods to the study of human-computer interaction. Specifically, we are interested in promoting a principled approach to the analysis and design of interactive systems that will accompany existing heuristic techniques. Previous formal approaches have concentrated on general and abstract mathematical models of interactive systems, proving that psychologically valid principles of interaction can be expressed in a language suitable for computation. Our efforts are focussed toward retaining the mathematical grounding of previous formalisms while providing additional insight and direction for design practice.

We introduce a unifying framework for the informal description of a user, a system and the interface that sits between them. We provide a mathematical model of the agent capable of expres sing interactive properties relating the goals of interaction with the visible consequences of that interaction. We also provide a language for agents which allows a natural expression of an agent's internal state-based behaviour and its external event-based behaviour and its external event-based behaviour. We contribute further to practical design issues by introducing templates to relate a task analysis to a specification of a system to support the tasks and an interface to adequately portray that functionality to the user. Finally, we initiate the formal investigation of multiagent architectures. This concludes the mapping of properties on abstract models of interactive sytems down to properties on more implementation-based models.