Verifying CTL-live properties of infinite state models using an SMT solver

Abstract

The ability to create and analyze abstract models is an important step in conquering software complexity. In this paper, we show that it is practical to verify dynamic properties of infinite state models expressed in a subset of CTL directly using an SMT solver without iteration, abstraction, or human intervention. We call this subset CTL-Live and it consists of the operators of CTL expressible using the least fixed point operator of the mu-calculus, which are commonly considered liveness properties (e.g., AF, AU). We show that using this method the verification of an infinite state model can sometimes complete more quickly than verifying a finite version of the model. We also examine modelling techniques to represent abstract models in first-order logic that facilitate this form of model checking.