Verifying Scr Requirements Speciications Using State Exploration

Researchers at the Naval Research Laboratory (NRL) have been developing a formal method, known as the SCR (Software Cost Reduction) method, to specify the requirements of software systems using tables. NRL has developed a formal state machine model de ning the SCR semantics and support tools for analysis and validation. Recently, a veri cation capability was added to the SCR toolset. Users can now invoke the Spin model checker within the toolset to establish properties of a speci cation. This paper describes the results of our initial experiments to verify properties of SCR requirements speci cations using Spin. After reviewing the SCR requirements method and introducing our formal requirements model, we describe how SCR speci cations can be translated into an imperative programming notation. We also describe how we limit state explosion by verifying abstractions of the original requirements speci cation. These abstractions are derived using the formula to be veri ed and special attributes of SCR speci cations. The paper concludes with the results of our experiments with Spin and a discussion of ongoing and future work.