Keywords:Real-world real-time systems may involve many complex structures, which are difficult to verify. We experiment with the model-checking of an applicationlayer html-based web-camera which involves structures like event queues, highlayer communication channels, and time-outs. To contain the complexity, we implement our verification tool with a newly developed BDD-like data-structure, reduced CRD (Clock-Restriction Diagram), which has enhanced the verification performance through intensive data-sharing in a previous report. However, the representation of reduced CRD does not allow for quick test of zone containment. To this purpose, we thus have designed a new CRD-based representation, cascade CRD, which has given us enough performance enhancement to successfully verifying several implementations of the web-camera.
Abstract.A new data-structure called RED (Region-Encoding Diagram) for the fully symbolic model-checking of real-time software systems is proposed. RED is a BDD-like data-structure for the encoding of regions [2]. Unlike DBM which records differences between pairs of clock readings, RED only uses one auxiliary binary variable for each clock. Thus the number of variables used in RED is always linear to the number of clocks declared in the input system description. Experiment has been carried out to compare RED with previous technologies.
Three numerical coverage metrics for the symbolic simulation of densetime systems and their estimation methods are presented. Special techniques to derive numerical estimations of dense-time state-spaces have also been developed. Properties of the metrics are also discussed with respect to four criteria. Implementation and experiments are then reported.
We extend a TCTL model-checking problem to a parametric timing analysis problem for real-time systems and develop new techniques for solving it. The algorithm we present here accepts timed transition system descriptions and parametric TCTL formulas with timing parameter variables of unknown sizes and can give back general linear equations of timing parameter variables whose solutions make the systems work.
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