APPLICATION OF FORMAL METHODS IN SYSTEM DESIGN.

The rise in complexity of modern systems has highlighted the shortcomings of ad-hoc design techniques. A need to put system design onto a more formal basis, as in many other engineering disciplines, is now widely accepted. This situation has led to the recent development of a range of mathematically based specification methods, each of which addresses some part of the design problem. The methods do not however tackle all the issues of importance in practical system development. It is the aim of this paper to show how the rigour of these new methods relate to the design process by putting formal and informal techniques in a common framework. The notion introduced here is that formal methods are components in a design environment which serve to support the user. A guide to the selection of an appropriate method is compiled here from practical experience.