(An) approach to defining and verifying modules for Statecharts

Abstract

Statecharts is a visual specification language widely used for specifying requirements of reactive system. The expressive power of Statecharts with features such as parallelism and hierarchy of statecharts makes it suitable for specifying large and complex systems. Analysis techniques like model checking facilitate to analyze the statecharts, but, unfortunately, suffer from the state-explosion problem. Therefore various techniques have been developed to cope with this problem. Among them, module-based assume-guarantee reasoning is adopted in our work to deal with this problem for the statecharts. For assume-guarantee reasoning, notions of modules, assumptions and guarantees are needed. Definition of modules in the statecharts includes notions of event scoping and assumptions about the environment. Using the statecharts module, we have designed an algorithms to make a guarantee of it under the given assumptions. To make a guarantee, we define a macro step model of the statecharts modules, and with this guarantee, a reduced macro step model is developed. We have conducted an empirical study with an example, Coffee Vending Machine, using the verification framework proposed by O. Grumberg et al[1]. As a result, we obtained reduced complexity, and further more we found the effectiveness of our method in the case of many internal states.