Software Design of System Requirements Utilizing Set Theory Model for Anomaly Handling
James A. Sanchez · INCOSE International Symposium · 1996
Abstract In 1995 Ronald Carson developed a mathematical model for system requirements analysis (SRA) utilizing set theory to explicitly treat unwanted or unexpected conditions that may be experienced by the system being analyzed. He showed that the SRA model can be used to derive completeness criteria. He claimed that the highest utility of the model would be found in the area of software requirements because of the focus on system states. A simple example using a Power Distribution Unit (PDU) was made in order to clarify the salient points. This simple example had only three states and six transitions, which were identified as nine antecedents (conditions which precede). Eight requirements were generated for the PDU. In this paper, the requirements for this simple example, along with its principles, are used to construct a simple software implementation in graphical fashion in order to test the effectiveness of the methodology for software. In conclusion, the SRA model utilizing elementary set theory needs some refinement for software applications. Though the method is rigorous, problems surface because of 1) ambiguities in language, 2) unforeseen conditions, 3) undefined initial conditions, and 4) probability density function of primitives. In addition, the start condition of the timers are undefined, as are the initial states of primitives, e.g. valid input, degraded input and inhibit output and degraded output.