ProbVerus: Probabilistic Symbolic Model Checking

Abstract

Model checking can tell us whether a system is correct; probabilistic model checking can also tell us whether a system is timely and reliable. Moreover, probabilistic model checking allows one to verify properties that may not be true with probability one, but may still hold with an acceptable probability. The challenge in developing a probabilistic model checker able to handle realistic systems is the construction of the state space and the necessity to solve huge systems of linear equations. To address this problem, we have developed ProbVerus, a tool for the formal verification of probabilistic real-time systems. ProbVerus is an implementation of probabilistic computation tree logic (PCTL) model checking using symbolic techniques. We present ProbVerus, demonstrate its use with a simple manufacturing example, and report the current status of the tool. With ProbVerus, we have been able to analyze, within minutes, the safety logic of a railway interlocking controller with 10²⁷ states.