Inconsistency-Based Strategy for Clarifying Vague Software Requirements

Abstract

It seems to be inevitable to confront vague information about customer’s needs during the software requirements stage. It may be desirable to record and clarify the vague information to avoid missing real requirements. In this paper, we provide an inconsistency-based strategy to handle vague information in the framework of Annotated Predicate Calculus. This strategy permits the stakeholder to describe the different vague information using statements with different levels of belief, where each level of belief is determined by the degree of vagueness. By checking consistency of the union of vague requirements and clear requirements, we then heighten the level of belief in uncontroversial vague requirements. We also lower the levels of belief in requirements involved in undesirable inferences and leave them to be articulated in some following stage. To support this, Annotated Predicate Calculus is used to represent the requirements specification. In particular, we present a special belief semilattice, which defines truth values appropriate for representing the strength of analyst’s belief in the truth of requirements statements.