An axiomatic approach of software functionality measure

Three axioms for functional complexity of software are proposed. The first axiom asserts that functional complexity is a function and is computable at the specification level. The second axiom argues that an empty specification has zero functional complexity. The third axiom asserts that a harder specification has no less functional complexity than an easier one. With these three axioms and various definitions of the notions of functional complexity, a number of theorems are proved. Code metrics, including statement count, M. Halstead´s (1977) programming effort, and T. McCabe´s cyclomatic number are reviewed, together with specification metrics including L. Hellerman´s (1972) metric, D. Schutt´s (1977) metric, N. Coulter´s (1987) metric, and A. Albrecht´s (1983) functional point. These metrics are evaluated with respect to the three axioms. Results show that code metrics do not satisfy these axioms, while Hellerman, Schutt, and Coulter metrics do