Formal user models and methods for reasoning about interactive behaviour

User models allow for usability decisions to be made about abstract system designs.Programmable User Models are one such approach to user modelling; theyhave been developed over the past decade so that they now cover a wide range of informal,semi-formal and fully formal approaches. In this paper we briefly review theapproaches investigated, thus setting out a context for Programmable User Modellingand propose a formal model of the cognitive assumptions that underly the approach.In...