Abstract

Model-checking is a method of verifying concurrent systems in which a state-graph model of the system behavior is compared with a temporal logic formula. This paper extends modelchecking to stochastic real-time systems, whose behavior depends on probabilistic choice and quantitative time. The specification language is TCTL, a branching-time temporal logic for expressing real-time properties. We interpret the formulas of the logic over generalized semiMarkov processes. Our model can express constraints like "the delay between the request and the response is distributed uniformly between 2 to 4 seconds". We present an algorithm that combines model-checking for real-time non-probabilistic systems with model-checking for finite-state discrete-time Markov chains. The correctness of the algorithm is not obvious, because it analyzes the projection of a Markov process onto a finite state space. The projection process is not Markov, so our most significant result is that the model-checking algo...

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