Conditional Refinement

Behavioral refinement and also interface refinement support only a rather idealistic view of system development, namely, that the final implementation behaves in accordance with the initial requirements specification for the whole spectrum of input histories. In practice, this is often unrealistic. In many cases there is a need to impose additional environment assumptions during the development. These environment assumptions are typically implementation-oriented and often not known in advance when the requirements specification is written. In other cases, they are too technical to be included in the requirements specification.