Refinement for Multiagent Protocols

An interaction protocol specifies a decentralized multiagent system operationally by specifying constraints on messages exchanged by its member agents. Engineering with protocols requires support for a notion of refinement, whereby a protocol may be substituted without loss of correctness by one that refines it. We identify two desiderata for refinement. One, generality: refinement should not restrict enactments by limiting protocols or infrastructures under consideration. Two, preservation: to facilitate modular verification, refinement should preserve liveness and safety. We contribute a novel formal notion of protocol refinement based on enactments. We demonstrate generality by tackling the declarative framework of information protocols. We demonstrate preservation by formally establishing that our notion of refinement is safety and liveness preserving. We show the practical benefits of refinement by implementing a checker. We demonstrate that it is less time-intensive to check refinement (and thereby gain safety and liveness) than to recheck safety and liveness of a composition.