Formalism and Informality in Software Development

Abstract

Because the machines we build are essentially formal we are obliged to formalise every problem to which we apply them. But the world in which the problem exists is rarely, if ever, formal. Formalisation of an informal reality is therefore a fundamental—though somewhat neglected—activity in software development. In this talk some aspects of the formalisation task are discussed, some techniques for finding better approximations to reality are sketched, and some inevitable limitations of formal models are asserted.