A Refinement Calculus for Requirements Engineering Based on Argumentation Theory

The Requirements Engineering (RE) process starts with initial requirements elicited from stakeholders – however conflicting, unattainable, incomplete and ambiguous – and iteratively refines them into a specification that is consistent, complete, valid and unambiguous. We propose a novel RE process in the form of a calculus where the process is envisioned as an iterative application of refinement operators, with each operator removing a defect from the current requirements. Our proposal is motivated by the dialectic and incremental nature of RE activities. The calculus, which we call CaRE, casts the RE problem as an iterative argument between stakeholders, who point out defects (ambiguity, incompleteness, etc.) of existing requirements, and then propose refinements to address those defects, thus leading to the construction of a refinement graph. This graph is then a conceptual model of an RE process enactment. The semantics of these models is provided by Argumentation Theory, where a requirement may be attacked for having a defect, which in turn may be eliminated by a refinement.