A software tool for learning about stochastic models

The Symbolic Hierarchical Automated Reliability/Performance Evaluator (SHARPE), a software system that analyzes stochastic models, is discussed. SHARPE allows students to set up and solve a variety of model types, to compare results for different models of the same system, to see how altering system parameters affects measures of effectiveness of the system, and to experiment with modeling techniques, including the use of exact and approximate system or model decomposition. It can also be used to illustrate problems of large state spaces and stiff systems and to provide examples of methods for avoiding these problems. Using SHARPE, one can specify and analyze the following model types separately or in combination: fault trees, reliability block diagrams, reliability graphs, product-form queuing networks, series-parallel acyclic directed graphs, Markov and semi-Markov chains, and generalized stochastic Petri nets