Program Semantics and a Verification Technique for Knowledge-Based Multi-Agent Systems

Abstract

We give a relational and a weakest precondition semantics with perfect recall, for concrete "knowledge-based programs", i.e., programs written in a general purpose programming language but with tests on knowledge. Using these knowledge-based programs, we define a program-epistemic logic to model complex epistemic properties of the execution of multi-agent systems. We give our logic a Kripke possible worlds semantics based on the observability of variables so as to richly express knowledge of agents who can or cannot observe said variables. We give a sound translation of the validity of program-epistemic logic formulas into first-order validity, using our weakest precondition semantics and an ingenious book-keeping of variable assignment. We implement our translation and fully automate our verification method for well-established examples using SMT solvers.