Internal consistency of FRSM specifications

Abstract In recent years, research on the integration of structured system analysis methods and formal methods to provide more effective tools for industrial-scale software development has grown. One tool that has been successfully designed on this basis is the formal requirements specification method (FRSM). FRSM is a structured formal language and method for requirements analysis and specification construction based on data flow analysis. An FRSM specification adopts an extended hierarchical DeMarco data flow diagram as its main frame and uses the pre- and postcondition structure in the operation definitions of the Vienna development method to specify the functionality of condition processes in the data flow diagram. When constructing FRSM specifications, internal consistency of the specifications needs to be ensured in order for correct requirements, system implementation, and verification to be achieved. Internal consistency is required because of the introduction of a pre- and postcondition structure for specifying the functionality of condition processes in FRSM specifications. It covers the following three aspects: consistency between postconditions and input data availability, consistency between pre- and postconditions, and consistency between condition processes. After a brief introduction of FRSM, this article discusses these three aspects in detail and provides corresponding methods to check them.