Representing and reasoning about preferences in requirements engineering

The priorities that stakeholders associate with requirements may vary from stakeholder to stakeholder and from one situation to the next. Differing priorities, in turn, imply different design decisions for the system to be. While elicitation of requirement priorities is a well-studied activity, modeling and reasoning with prioritization has not enjoyed equal attention. In this paper, we address this problem by extending a state-of-the-art goal modeling notation to support the representation of preference (“nice-to-have”) requirements. In our extension, preference goals are distinguished from mandatory ones. Then, quantitative prioritizations of the former are constructed and used as criteria for evaluating alternative ways to achieve the latter. To generate solutions, an existing preference-based planner is utilized to efficiently search for alternatives that best satisfy a given set of mandatory and preferred requirements. With such a planning tool, analysts can acquire a better understanding of the impact of high-level stakeholder preferences on low-level design decisions.