A Refinement Relation Supporting the Transition from Unbounded to Bounded Communication Buffers

This paper proposes a refinement relation supporting the transition from unbounded to bounded communication buffers. Employing this refinement relation, a system specification based on purely asynchronous communication can for example be refined into a system specification where the components communicate purely in terms of handshakes. First a weak version called partial refinement is introduced. Partial refinement guarantees only the preservation of safety properties — preservation in the sense that any implementation of the more concrete specification can be understood as an implementation of the more abstract specification if the latter is a safety property. This refinement relation is then strengthened into total refinement which preserves both safety and liveness properties. Thus a total refinement is also a partial refinement. The suitability of this refinement relation for top-down design is discussed and some examples are given.