Safety analysis in formal specication

Formal methods give us techniques to specify the functionality of a system, to verify its correctness or to develop the system stepwise from an abstract specification to its implementation. These aspects are important when designing safety-critical systems. Safety analysis is a vital 1 part of the development of such systems. However, formal methods seldom interface well with the more informal techniques developed for safety analysis. Action systems is a formal approach to distributed computing that has proven its worth in the design of safety-critical systems. The approach is based on a firm mathematical foundation within which the reasoning about the correctness and behaviour of the system under development is carried out. The purpose of this paper is to show how we can incorporate the results of safety analysis into an action system specification by encoding this information via available composition operators for action systems in order to specify robust and safe controllers.