We describe DRA (demonic Re nement Algebra), a variation of KAT for total correctness and illustrate its modeling and reasoning power with a number of applications and examples.Expand

We show how to formalise different kinds of loop constructs within the refinement calculus, and how to use this formalisation to derive general transformation rules for loop constructs.Expand

We extend von Wright's refinement algebra with two operators for modelling enabledness and termination of programs in a total-correctness framework.Expand

We define a weakest precondition semantics for contracts that permits us to compute the initial states from which a group of agents has a winning strategy to reach their goal.Expand

To the Editor.â€” The weight of evidence, recently reviewed, 1 suggests that vitamin E reduces the risk of thromboembolic disorders. This nutrient appears to inhibit platelet aggregation directly 1,2â€¦ Expand