Minimizing Commit Rules for DAG-based Atomic Broadcast

Abstract

A popular class of Byzantine fault-tolerant atomic broadcast protocols rely on directed acyclic graphs (DAGs) that represent causal relations between broadcast messages. Each process applies a protocol-specific commit rule on its local DAG to determine which vertices can be delivered in a total order. Intuitively, commit rules that impose fewer conditions on the DAG to order its vertices imply more efficient protocols, as the broadcast messages are delivered with lower latency. In this paper, we define commit rules on an uncertified round-based DAG construction, and introduce a sub-rule relation between them: a commit rule $cr_1$ is a sub-rule of a commit rule $cr_2$ if, for any DAG, the set of vertices committed by $cr_1$