An Approach to Declaring Data Types for Formal Specifications

Abstract

Data type declaration is an important activity in formal specification construction, which results in a collection of custom types for defining variables to be used in writing formal expressions such as pre- and post-conditions. As the complexity of software products rises, such a task will become more and more difficult to be handled by practitioners. This paper proposes an approach to facilitate the declaration of data types based on a set of function patterns, each designed for guiding the description of one kind of function in formal expressions. During the application of these patterns, necessary data types will be automatically recognized and their definitions will be gradually refined. Meanwhile, formal expressions will be modified to keep their consistency with the type definitions. A case study on a banking system is presented to show the validity of the approach in practice.