Literate Formal Development Of Ada From Z For Safety Critical Applications

This paper describes an approach to the formal speciication and subsequent development of software which permits various degrees of formality and rigour to be employed according to the degree of risk. The aim is to allow safety critical and non-critical code to be developed to the appropriate degrees of rigour in the same development environment. The technique, introduced by an illustrative example, is designed to allow Ada programs to be developed in a literate fashion within the context of a development document incorporating a Z speciication. It is supported by a suite of tools for checking the consistency and correctness of the development. These tools have been used in the production of this paper.