Behavioral Specification of Reactive Systems Using Stream-Based I/O Tables

A core problem in formal methods is the transition from informal requirements to formal specifications. Especially when specifying reactive systems, many formalisms require the user to either understand a complex mathematical theory and notation or to derive details not given in the requirements, such as the state space of the problem. While formalizing a real-world requirements document, we developed a technique where not states but signal patterns are the main elements. We argue that it supports a formalization that is often closer to the informal requirements and thus provides a smoother transition to formal methods. As only tables of regular expressions are used for notation, the technique can easily be understood by non-mathematicians. Many properties, such as consistency, can be checked automatically on these specifications. Besides the formal foundation of our approach, this paper presents prototypical tool support and first results from an industrial case study.