Symmetric and Synchronous Communication in Peer-to-Peer Networks

Motivated by distributed implementation of game-theoretical algorithms, we study symmetric systems, i.e. systems of processes which are intuitively "treated on an equal footing", and the problem of attaining common knowledge between processes. We formalize our setting by defining peer-to-peer networks and appropriate symmetry notions in the context of Communicating Sequential Processes (CSP), due to the common knowledge creating effects of its synchronous communication primitives. We then prove that CSP with input and output guards makes common knowledge in symmetric peer-to-peer networks possible, but not the restricted version which disallows output statements in guards and is commonly implemented.