Task Modelling in Multiple Contexts of Use

The context of use in which users are carrying out their interactive tasks is continuously submitted to an evolution in the user population, the computing platforms used for the tasks, and the physical environment in which users are living. This evolution process raises a need for extending traditional task modelling to support multiple contexts of use simultaneously. To address this problem, this paper first provides a formal notation of a task model that is further refined to support the variation of conditions depending on multiple contexts of use. Key concepts are then introduced to support the task modelling process so as to create a clear frontier between the Context-dependent Task Model and the Context-Independent Task Model. The ContextPartially-Independent Task Model attempts to capture subtasks shared in many contexts of use, but not all. The use of these key concepts enable designers to build a Multi-Context Task Model, notably, by factoring out common parts from Context-dependant Task Models. All these key concepts are equally denoted with the introduced formal notation. In addition, they support designers in adopting the task modelling approach of their choice in multiple contexts of use, which is so far not allowed.