Refinement in Z and Object-Z
- DPhil John Derrick BSc, PhD Eerke Boiten Ir
- Computer ScienceFormal Approaches to Computing and Information…
- 2001
Although internal operations decrease the variant E, there are no constraints on observable operations, which are allowed to increase the variant, which means that an internal operation can be invoked an infinite number of times, but not in an infinite sequence between observable operations.