Hoare and He's unifying theories of programming (UTP) is a model of alphabetised relations expressed as predicates; it supports development in several programming paradigms. T...
The refinement calculus of Back, Morgan, Morris, and others is based on monotone predicate transformers (weakest preconditions) where conjunctions stand for demonic choices betwee...
The abstraction inherent in most specifications and the need to specify nondeterministic programs are two well-known sources of nondeterminism in formal specifications. In this pap...