Release time decision policy of software employed for the safety of critical system under uncertainty

Critical systems exist all around us, from nuclear power plants to chemical processing plants to heart monitors and emergency phone systems etc. As software and processors encompass critical systems, the risk involved because of software failure is unimaginable. The main emphasis of software industries developing these systems is to put a great deal of deliberation and thought into making these systems as safe as possible. Safety is a nebulous concept, and is therefore difficult to define or measure. In our paper we measure safety in the form of risk and the costs associated with it. We have formulated an optimization problem for determining the optimal time at which the software testing is stopped and system is ready for use in operational phase with the prime objective of minimizing risk cost subject to budget constraints and failure intensity. We have also considered uncertainty and ambiguities in the definition of cost function and risk function coefficients, available budget, failure intensity due to intense competition in the global market, varying requirements of the client, rapid evolution of information technology, system complexity, intended flexibility, poor data base to name a few. For this we have defined the constrained optimization problem under fuzzy environment. Finally we have discussed fuzzy optimization technique for solving the problem with a help of numerical illustration.