Specification of required non-determinism

We present an approach to the specification of required external non-determinism: the willingness of a component to respond to a number of external action requests, using a language, COMMUNITY, which provides both permission and willingness guards on actions. This enables a program-like declaration of required non-determinism, in contrast to the use of a branching-time temporal logic. We give a definition of parallel composition for this language, and show that refinement is compositional with respect to parallel composition. We use the concepts developed for COMMUNITY to identify extensions to the B and VDM++ model-based specification languages to incorporate specification of required non-determinism. In particular, we show that preconditions may be considered as a form of willingness guard, separating concerns of acceptance and termination, once module contracts are re-interpreted in a way suitable for a concurrent environment

Specification of Required Non-determinism

We present an approach to the specification of required external non-determinism: the willingness of a component to respond to anumber of external action requests, using a language, COMMUNITY, which provides both permission and willingness guards on actions. This enables a program-like declaration of required non-determinism, in contrast to the use of a branching-time temporal logic. We give a definition of parallel composition for this language, and show that refinement is compositional with respect to parallel composition. We use the concepts developed for COMMUNITY to identify extensions to the B and VDM ++ model-based specification languages to incorporate speci cation of required non-determinism. In particular, we show that preconditions may be considered as a form of willingness guard, separating concerns of acceptance and termination, once module contracts are re-interpreted in away suitable for a concurrent environment