Formal Requirements in an Informal World

With today's increasing complexity of systems and requirements there is a need for formal analysis of requirements. Although there exist several formal requirements description languages and corresponding analysis tools that target an industrial audience, there is a large gap between the form of requirements and the training in formal methods available in industry today, and the form of requirements and the knowledge that is necessary to successfully operate the analysis tools. We propose a process to bridge the gap between customer requirements and formal analysis. The process is designed to support in-house formalisation and analysis as well as formalisation and analysis as a service provided by a third party. The basic idea is that we obtain dependability and comprehensibility by assuming a senior formal requirements engineer who prepares the requirements and later interprets the analysis results in tandem with the client. We obtain scalability as most of the formalisation and analysis is supposed to be conducted by junior formal requirements engineers. In this paper, we define and analyse the process and report on experience from different instantiations, where the process was well received by customers.