Describing and analyzing behaviours over tabular specifications using (Dyn)alloy

Abstract

We propose complementing tabular notations used in requirements specifications, such as those used in the SCR method, with a formalism for describing specific, useful, subclasses of computations, i.e., particular combinations of the atomic transitions specified within tables. This provides the specifier with the ability of driving the execution of transitions specified by tables, without the onerous burden of having to introduce modifications into the tabular expressions; thus, it avoids the problem of modifying the object of analysis, which would make the analysis indirect and potentially confusing. This is useful for a number of activities, such as defining test harnesses for tables, and concentrating the analyses on particular, interesting, subsets of computations. Unlike previous approaches, ours allows for the description of a wider class of combinations of the transitions defined by tables, by means of a rich operational language. This language is an extension of the Alloy language, called DynAlloy, whose notation is inspired by that of dynamic logic. The use of DynAlloy enables us to provide an extra mechanism for the analysis of tabular specifications, based on SAT solving. We will illustrate this and the features of our approach via an example based on a known tabular specification of a simple autopilot system.