Non-monotonic modelling from initial requirements

Abstract

Researchers make a significant effort to develop new modelling languages and tools. However, they spend less effort developing methods for constructing models using these languages and tools. We are developing a method for building an embedded system model for formal verification. Our method provides guidelines to build a model and to construct a correctness argument. We start from a high-level formula stating that a plant (a device that performs a task) and its control should satisfy requirements. As our knowledge about the system grows, we refine this formula and the model gradually, in a stepwise non-monotonic process, until we have a description that can be formally verified. In this paper we explain our method on a simple example and compare it briefly with two other methods: requirements progression and the goal-oriented KAOS approach. The requirements progression is an extension of a problem frames approach. The KAOS method is also based on problem frames, but introduces new concepts for describing a system.