Model Checking Temporal Logics of Knowledge Via OBDDs

Model checking is a promising approach to automatic verification, which has concentrated on specification expressed in temporal logics. Comparatively little attention has been given to temporal logics of knowledge, although such logics have been proven to be very useful in the specifications of protocols for distributed systems. In this paper, we address ourselves to the model checking problem for a temporal logic of knowledge (Halpern and Vardi’s logic of CKLn). Based on the semantics of interpreted systems with local propositions, we develop an approach to symbolic CKLn model checking via OBDDs and implement the corresponding symbolic model checker MCTK. In our approach to model checking specifications involving agents’ knowledge, the knowledge modalities are eliminated via quantifiers over agents’ non-observable variables. We verify the anonymity property of the dining cryptographers protocol in MCTK and two other epistemic model checkers, MCK and MCMAS, and compare the experimental results.