Automatic Integration of Safety Invariants into ZSpeci cations

This extended abstract describes a mechanism to automatically incorporate safety requirements into operational speciications written in Z. For every individual operation the global (i.e. operation independent) safety invariants are transformed into a predicate which is used to extend the original precondition of the operation. The operation constructed this way shows the same behavior as the original one whenever its post state satisses the invariant. Otherwise it refuses to do anything. The construction of the precondition can be carried out automatically and a corresponding tool development is in progress.