A State-based Refinement Technique for Event-B

Abstract

Formal models can be used to describe and reason about the behavior and properties of a given system. In some cases, it is even possible to prove that the system satisfies the given properties. This allows detecting design errors and inconsistencies early and fixing them before starting development. Such models are usually created using stepwise refinement: starting with the simple, abstract model of the system, and then incrementally refining it adding more details at each subsequent level of refinement. Top levels of the model usually describe the high-level design or purpose of the system, while the lower levels are more directly comparable with the implementation code. In this paper, we present a new, alternative refinement technique for Event-B which can simplify the development of complicated models with a large gap between high-level design and implementation.