Modelling user structures within system specifications

The use of mathematical specification techniques is gaining momentum within industry and commerce. However much work still needs to be done to improve these techniques to make them more practically feasible. The author concentrates on a particular problem-that the user´s conceptual model of how a system works may conflict with the designer´s understanding of how the user will view the system. There are two facets to the problem. First, mathematical specification is no way to communicate to the user how a system will look and feel. Second, mathematical models of interactive systems should incorporate claims, structures or principles about how the system will be used or understood. The author concentrates on the second facet by briefly discussing a database system. He shows how user-recognisable structures may be formulated and used in establishing criteria for designing and evaluating interactive systems, taking a software engineering approach