Refinement of statemachines using hierarchical states , choice points and joins

While refinement gives a formal underpinning to the development of dependable control systems, such models are difficult to communicate and reason about in a non-formal sense, particularly for validation by non-specialist industrial partners. Here we present a visualisation of event B refinement using a specialisation of UML statemachines. The specialisation will be incorporated into the UML-B notation that is being re-developed within the Rodin project to improve integration with the Event B platform, which is also being developed by the Rodin project.