Formal Veri cation of Performance and Reliability of Real-Time Systems

In this paper we propose a methodology for the speci cation and veri cation of performance and reliability properties of real-time systems within the framework of temporal logic. The methodology is based on the system model of stochastic real-time systems (SRTSs), and on branching-time temporal logics that are extensions of the probabilistic logics pCTL and pCTL*. SRTSs are discrete-time transition systems that can model both probabilistic and nondeterministic behavior. The speci cation language extends the branching-time logics pCTL and pCTL* by introducing an operator to express bounds on the average time between events. We present model-checking algorithms for the algorithmic veri cation of system speci cations, and we discuss their complexity. This research was supported in part by the National Science Foundation under grant CCR-92-23226, the Advanced Research Projects Agency under NASA grant NAG2-892, the United States Air Force O ce of Scienti c Research under grant F49620-93-1-0139, and the Department of the Army under grant DAAH0495-1-0317.