A pragmatic approach to the formal specification of interactive systems

In the thesis an approach to the formal specification of interactive systems which embodies a number of pragmatic criteria is presented. The criteria we use for pragmatism are that any proposed approach to specification should directly support usability reasoning, that the specifications should be expressive, and that they should be reusable. We examine the concept of usability reasoning, and use a model of reasoning which includes as components representation, input, observation, system behaviour and object structuring. Frameworks for reasoning about these components, and syntheses of these components are proposed. Expressiveness and reuse issues are examined in an object-oriented context, and two models of object interaction examined with respect to a number of criteria. Based on the understanding gained from exploration of these issues of reasoning, expressiveness and reuse, we develop an approach to the specification of interactive systems. We build on the existing notation of Object Z, but present a new schema calculus to allow interactive behaviour to be described more conveniently. To demonstrate its pragmatism, we apply this approach to a substantial case study.