TCTL Inevitability Analysis of Dense-Time Systems: From Theory to Engineering

Inevitability properties in branching temporal logics are of the syntax foralldiamphi, where phi is an arbitrary (timed) CTL (computation tree logic) formula. Such inevitability properties in dense-time logics can be analyzed with the greatest fixpoint calculation. We present algorithms to model-check inevitability properties. We discuss a technique for early decision on greatest fixpoint calculation which has shown promising performance against several benchmarks. We have experimented with various issues which may affect the performance of TCTL inevitability analysis. Specifically, our algorithms come with a parameter for the measurement of time-progress. We report the performance of our implementation with regard to various parameter values and with or without the non-Zeno computation requirement in the evaluation of greatest fixpoints. We have also experimented with safe abstraction techniques for model-checking TCTL inevitability properties. The experiment results help us in deducing rules for setting the parameter for verification performance. Finally, we summarize suggestions for configurations of efficient TCTL inevitability evaluation procedure