A Formal Approach to the Assessment of Priorities of Imprecise Con icting Requirements

Two major challenges with requirement engineering are (1) requirements are often imprecise in nature, and (2) requirements are usually connicting with each other. One of the most important issues in the trade-oo analysis of connicting requirements is to understand the priority of requirements. Existing formal methods for requirement engineering are very limited in addressing these issues. This paper presents a formal methodology for specifying imprecise requirements, for characterizing complex relationships among them, for assessing their priority, and for facilitating the trade-oo analysis. Imprecise requirements are represented by the canonical form in test-score semantics in fuzzy logic. Two kinds of relationships between requirements (i.e., connicting and cooperative) are formally introduced. Multiple requirements with diierent priorities are aggregated based on the fuzzy multi-criteria decision technique. The assessment of the priority of requirements is facilitated by analyzing the trade-oo between partial satisfaction of these imprecise requirements. The proposed approach can contribute not only to an early identiication of connicting requirements, but also to a better understanding the nature of connict, which is vital to the negotiation process and the trade-oo analysis during the design phase.