The Expressive Power of Synchronizations

A synchronization is a mechanism allowing two or more processes to perform actions at the same time. We study the expressive power of synchronizations gathering more and more processes simultaneously. We demonstrate the non-existence of a uniform, fully distributed translation of Milner\´s CCS with synchronizations of n + 1 processes into CCS with synchronizations of n processes that retains a "reasonable\´\´ semantics. We then extend our study to CCS with symmetric synchronizations allowing a process to perform both inputs and outputs at the same time. We demonstrate that synchronizations containing more than three input/output items are encodable in those with three items, while there is an expressivity gap between three and two.