Modularization of Refinement Steps for Agile, Formal Methods

Abstract

The combination of agile methods and formal methods has been recognized as a promising field of research. However, many formal methods rely on a refinement-based development process which poses problems for their integration into agile processes. We consider redundancies within refinement hierarchies as a challenge for the practical application of stepwise refinement and propose superimposition-based modularization of refinement steps as a potential solution. While traditionally, each model in a refinement hierarchy must be developed and maintained separately, our concept allows developers to specify the refinement steps that transform a model into a refined one. We have developed tool support for the language AsmetaL and evaluated our approach by means of a case study. The results indicate a reduction of complexity for the development artifacts in terms of their overall size by 48.6% for the ground model and four refinements. Furthermore, the case study shows that superimposition-based refinement eases the development of alternative refinements for exploratory development and to cope with changing requirements. Thus, we consider this work as a step towards agile formal methods that are tailored to support iterative development, facilitating their incorporation into agile development processes.