System Design as a Creative Mathematical Activity

This paper contributes to the understanding of rational systems design and verification. We give evidence that the rôle of mathematics in development and verification is not limited to useful calculations: Ideally, designing is a creative mathematical activity, which comprises finding a theorem, if necessary strengthening its assumptions until it can be proven. A canonical form of this ‘verification theorem’ is introduced and illustrated with informal and formal examples. Although for good reasons most systems are designed without use of formal methods it may be a source of useful insight to understand all design as an ‘approximation’ of such a mathematical activity. This leads amongst others to a taxonomy of design decisions, and it may help to relate paradigms, theories, methods, languages, and tools from different areas of computer science to each other to make optimal use of them.