A State Minimization Technique for TimedAutomata

The state space of a real-time system can result in an innnite number of states due to unbounded time values. For automatic analysis based on state space exploration, it is important to be able to nitely represent the state space of a real-time system. In this paper, we present an approach that produces a compact representation of the reachable state space of a real-time system. The algorithm yields a small state space, but still retains enough information for analysis. To avoid the state explosion which can be caused by simply adding time values to states, our approach rst uses history equivalence and transition bisimulation to collapse states into equivalent classes. To experiment with effectiveness of our approach, we have developed an automatic analysis tool called TREAT. This paper includes the experimental result on Fisher's mutual exclusion protocol.