Ideal specification formalism = expressivity + compositionality + decidability + testability + ...

Abstract

For the comparison of specification formalisms several criteria may be applied. In this paper we concentrate on the formalization of expressivity and compositionality. We apply these criteria to a number of specification formalisms ranging from behavioural formalisms (based on labelled transition systems) to logical formalisms (based on Hennessy-Milner logic). A main result of the paper is that a specification formalism must be at least as expressive as Hennessy-Milner Logic in order for specifications to be decomposable. Another main result is that implicit behavioural specifications are at least as expressive as logical specifications and do allow specifications to be decomposed. We also present specification formalisms for probabilistic processes, and evaluate these with respect to compositionality.