Dynamic availability is the ability of a consensus protocol to remain live despite honest participants going offline and later rejoining. A well-known limitation is that dynamically available protocols, on their own, cannot provide strong safety guarantees during network partitions or extended asynchrony. Ebb-and-flow protocols [SP21] address this by combining a dynamically available protocol with a partially synchronous finality protocol that irrevocably finalizes a prefix. We present Majorum, an ebb-and-flow construction whose dynamically available component builds on a quorum-based protocol (TOB-SVD). Under optimistic conditions, Majorum finalizes blocks in as few as three slots while requiring only a single voting phase per slot. In particular, when conditions remain favourable, each slot finalizes the next block extending the previously finalized one.
@article{arxiv.2601.03862,
title = {Majorum: Ebb-and-Flow Consensus with Dynamic Quorums},
author = {Francesco D'Amato and Roberto Saltini and Thanh-Hai Tran and Yann Vonlanthen and Luca Zanolini},
journal= {arXiv preprint arXiv:2601.03862},
year = {2026}
}