Verifying Clocked Transition Systems

This paper presents a new computational model for real-time systems, called the clocked transition system (cts) model. The cts model is a development of our previous timed transition model, where some of the changes are inspired by the model of timed automata. The new model leads to a simpler style of temporal speciication and veriication, requiring no extension of the temporal language. We present veriication rules for proving safety properties (including waiting-for and time-bounded response properties) of clocked transition systems, and separate rules for proving (time-unbounded) response properties. All rules are associated with veriication diagrams. The veriication of response properties requires adjustments of the proof rules developed for untimed systems, reeecting the fact that progress in the real time systems is ensured by the progress of time and not by fairness. The style of the veriication rules is very close to the veriication style of untimed systems which allows the (re)use of veriication methods and tools, developed for untimed reactive systems, for proving properties of real-time systems.