Brief Announcement: Null Messages, Information and Coordination

This paper investigates how null messages can transfer information in fault-prone synchronous systems. The notion of an f -resilient message block is defined and is shown to capture the fundamental communication pattern for knowledge transfer. In general, this pattern combines both null messages and explicit messages. It thus provides a fault-tolerant extension of the classic notion of a message-chain. Based on the above, we provide tight necessary and sufficient characterizations of the generalized communication patterns that can serve to solve the distributed tasks of (nice-run) Signalling and Ordered Response.