A theory of user-interaction objects

A general theory is presented which formally describes user interface systems that manage communications between users and applications. Its purpose is to provide the formal semantics of a large spectrum of user interface systems by means of interaction objects which have been mathematically defined. The main features of this approach are that the relationships between input and output functionalities are completely addressed, and these systems are uniformly described by a multilayered composition of interaction objects derived from a specific architectural model for basic interactions with users. Within the framework thus obtained we make comparisons between different instances of interactive visual environments in order to establish whether their behaviour is equivalent at least for some aspects, and we give examples of properties that can be investigated. © 1994 Academic Press Limited.