QBF Encoding of Temporal Properties and QBF-Based Verification

Abstract

SAT and QBF solving techniques have applications in various areas. One area of the applications of SAT-solving is formal verification of temporal properties of transition system models. Because of the restriction on the structure of formulas, complicated verification problems cannot be naturally represented with SAT-formulas succinctly. This paper investigates QBF-applications in this area, aiming at the verification of branching-time temporal logic properties of transition system models. The focus of this paper is on temporal logic properties specified by the extended computation tree logic that allows some sort of fairness, and the main contribution of this paper is a bounded semantics for the extended computation tree logic. A QBF encoding of the temporal logic is then developed from the definition of the bounded semantics, and an implementation of QBF-based verification follows from the QBF encoding. Experimental evaluation of the feasibility and the computational properties of such a QBF-based verification algorithm is reported.