Where, Exactly, Is Software Development?

摘要

Viewed narrowly, software development is concerned only with formal computations; viewed more broadly, it is concerned also with the problem world outside the computer. The broader view compels us to deal with the physical and human world by formalisations that bring it within the scope of formal reasoning, allowing us to deal effectively with the causal chain that relates the customer's requirements to the formally described external behaviour of the computer. It offers not only a sparsely explored field of application for formal techniques, but also fresh challenges that can contribute to shaping and extending those techniques. The primary challenge centres on the impossibility of exact true description of the problem world: any description is only an approximation to the reality. Appropriate specification and design structures can achieve the reliability and extensibility necessary for each particular system. The study of such structures merits an important place in computer science.