Verification of Clock Synchronization Algorithms: Experiments on a combination of deductive tools

Damian Barsotti (1) , Leonor Prensa Nieto (2) , Alwen Tiu (3)

1 FaMAF - Facultad de Matemática, Astronomía y Física [Cordoba]
2 MOSEL - Proof-oriented development of computer-based systems
3 Research School of Information Sciences and Engineering

We report on an experiment in combining the theorem prover Isabelle with automatic first-order arithmetic provers to increase automation on the verification of distributed protocols. As a case study for the experiment we verify several averaging clock synchronization algorithms. We present a formalization of Schneider's generalized clock synchronization protocol in Isabelle/HOL. Then, we verify that the convergence functions used in two clock synchronization algorithms, namely, the Interactive Convergence Algorithm (ICA) of Lamport and Melliar-Smith and the Fault-tolerant Midpoint algorithm of Lundelius-Lynch, satisfy Schneider's general conditions for correctness. The proofs are completely formalized in Isabelle/HOL. We identify parts of the proofs which are not fully automatically proven by Isabelle built-in tactics and show that these proofs can be handled by automatic first-order provers with support for arithmetics.

Domaines: Logique en informatique [cs.LO]

Damian Barsotti, Leonor Prensa Nieto, Alwen Tiu. Verification of Clock Synchronization Algorithms: Experiments on a combination of deductive tools. Formal Aspects of Computing, 2007, 19 (3), pp.321-341. ⟨10.1007/s00165-007-0027-6⟩. ⟨inria-00097383⟩