Algebraic Specifications and Sequencing: A Defect Detection Method

One class of program defects results from illegal sequences of otherwise legal operations in software implementations. Explicit statement of sequencing constraints, however, is not a common activity when specifying software even when using formal speciication methods. This paper shows that constraints on program execution sequences can be derived directly from algebraic speciications. Results include heuristic methods for generating sequencing constraints and a generalization of these methods into automatable rules. The heuristics can be integrated into a speciication methodology such as Larch. Engineers can use the generated sequencing constraints to detect sequencing defects in software even before dynamic testing begins. The method can be used to increase the reliability of software that is speciied using algebraic methods.