The refinement technique allows us to capture the relationship between specification and implementation in software developments. The precise documentation of the refinement relationship makes it possible to trace the requirements through the refinement steps. Unfortunately, the standard modeling language UML suffers from a lack of notation to specify refinements in a precise way; in particular...

Formal verification of algorithms often requires a choice between definitions that are easy to reason about and definitions that are computationally efficient. One way to reconcile both consists in adopting a high-level view when proving correctness and then refining stepwise down to an efficient low-level implementation. Some refinement steps are interesting, in the sense that they improve the...