Abstract
We consider that nondeterministic programs behave as badly as they can and loop forever whenever they have the possibility to do so. We deal with a relational algebra model to define a nondeterministic refinement fuzzy ordering (nondeterministic fuzzy inclusion) and also the associated fuzzy operations which are fuzzy nondeterministic join (u), fuzzy nondeterministic meet (n z), and fuzzy nondeterministic composition (0 ft). We also give some properties of these operations and illustrate them with simple examples.