What Belongs to Context? - A Definition, a Criterion and a Method for Deciding on What Context-Aware Systems Should Sense and Adapt to

Context-awareness refers to the ability to sense and adapt to context. With the rise of context-aware systems, designers are struggling with what variables should be sensed from the context. According to the definitions found in the literature, whether something belongs to context, has to do with whether it is relevant. However, what it means to be relevant is left implicit in these definitions. Most work on context-aware systems is based on assumptions of the context that should be taken into account. Hence, it is unclear how to decide whether something belongs to context or should be left out. In this paper, first we analyse what is meant with context and provide a definition. In this definition we introduce the notion of a context variable, defined as an attribute of an object that is relevant. Context is then defined as the set of context variables. We establish explicit criteria for deciding whether an attribute of an object is a context variable based on the proposed definition and the designer’s goal. We also provide a straightforward method to help designers to determine whether the criterion is met and a variable should be included in the context. This method is based on filling out a scheme to describe context variables.