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Implications of M&S Foundations for the V&V of Large Scale Complex Simulation Models

While there are no general tools that would ease the V&V process for large scale complex models, there is a theory and framework to support the development of such tools. In this review of the theory and framework, we discuss the possibility of universal V&V tools that are entirely domain-independent in the sense that they operate with concepts that are applicable to any model independently of its domain semantics. As background for this discussion, we review the major formalisms that are relevant to M&S, particularly from the V&V perspective. We find that a major trend in software development, object-orientation and the Unified Modeling Language, is not adequate for the specific requirements of M&S, which supercede those of general software development. This motivates our review of systems theory and the theory of modeling and simulation based on it. As one application, we show how the theory-based concepts enable a systematic guideline to the role of V&V in the various key steps of the High Level Architecture Federation Development and Execution Process (FEDEP). The approach incrementally introduces appropriate levels/kinds of verification and validation activities throughout the FEDEP, and thus making it possible to handle the complexity inherent in V&V of distributed, legacy-based simulations. We also discuss the theory's support for V&V within the model composability problem and in component-based model development and reuse. Finally, we close with recommendations for further research in the development of universal tools for V&V of very large scale simulation models. We show how such tools can be based on computationally feasible domain-independent spaces that are conceivable within the spirit of general systems theory and that offer advantageous comparison of complex dynamical behaviors. It is also appropriate to warn the reader on what this review does not attempt to do. There is an abundance of concepts, methods, techniques, and tools to relating verification, validation, and accreditation in the various literatures of engineering, science and defense. Despite some attempts at categorization, these various techniques are only loosely related to one another and fail to display any obvious commonality. While we believe that eventually all such techniques could well be integrated into the framework we discuss here, we do not make any attempt in this paper. We do believe that such integration would benefit from research in the future.