DejaVu: A Minimalistic Mechanism for Distributed Plurality Consensus

Fuente: arXiv
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Main Authors: d'Amore, Francesco, D'Archivio, Niccolò, Giakkoupis, George, Giroire, Frédéric, Natale, Emanuele
Format: Preprint
Published: 2026
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author d'Amore, Francesco
D'Archivio, Niccolò
Giakkoupis, George
Giroire, Frédéric
Natale, Emanuele
author_facet d'Amore, Francesco
D'Archivio, Niccolò
Giakkoupis, George
Giroire, Frédéric
Natale, Emanuele
contents We study the plurality consensus problem in distributed systems where a population of extremely simple agents, each initially holding one of $k$ opinions, aims to agree on the initially most frequent one. In this setting, $h$-majority is arguably the simplest and most studied protocol, in which each agent samples the opinion of $h$ neighbors uniformly at random and updates its opinion to the most frequent value in the sample. We propose a new, extremely simple mechanism called DéjàVu: an agent queries neighbors until it encounters an opinion for the second time, at which point it updates its own opinion to the duplicate value. This rule does not require agents to maintain counters or estimate frequencies, nor to choose any parameter (such as a sample size $h$); it relies solely on the primitive ability to detect repetition. We provide a rigorous analysis of DéjàVu that relies on several technical ideas of independent interest and demonstrates that it is competitive with $h$-majority and, in some regimes, substantially more communication-efficient, thus yielding a powerful primitive for plurality consensus.
format Preprint
id arxiv_https___arxiv_org_abs_2604_03648
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle DejaVu: A Minimalistic Mechanism for Distributed Plurality Consensus
d'Amore, Francesco
D'Archivio, Niccolò
Giakkoupis, George
Giroire, Frédéric
Natale, Emanuele
Distributed, Parallel, and Cluster Computing
Multiagent Systems
We study the plurality consensus problem in distributed systems where a population of extremely simple agents, each initially holding one of $k$ opinions, aims to agree on the initially most frequent one. In this setting, $h$-majority is arguably the simplest and most studied protocol, in which each agent samples the opinion of $h$ neighbors uniformly at random and updates its opinion to the most frequent value in the sample. We propose a new, extremely simple mechanism called DéjàVu: an agent queries neighbors until it encounters an opinion for the second time, at which point it updates its own opinion to the duplicate value. This rule does not require agents to maintain counters or estimate frequencies, nor to choose any parameter (such as a sample size $h$); it relies solely on the primitive ability to detect repetition. We provide a rigorous analysis of DéjàVu that relies on several technical ideas of independent interest and demonstrates that it is competitive with $h$-majority and, in some regimes, substantially more communication-efficient, thus yielding a powerful primitive for plurality consensus.
title DejaVu: A Minimalistic Mechanism for Distributed Plurality Consensus
topic Distributed, Parallel, and Cluster Computing
Multiagent Systems
url https://arxiv.org/abs/2604.03648