DéjàVu: A Minimalistic Mechanism for Distributed Plurality Consensus

2026-04-04

AI Summary

This work addresses the problem of achieving majority consensus on the initially most frequent opinion among a large population of minimalist agents in distributed systems. The authors propose DéjàVu, a novel mechanism wherein agents adopt a value solely by detecting its recurrence among neighbors—without requiring explicit counting, frequency estimation, or any predefined parameters. Grounded in probabilistic sampling and theoretical analysis, DéjàVu substantially simplifies protocol design while enhancing communication efficiency. Experimental results demonstrate that DéjàVu achieves accuracy comparable to h-majority across diverse scenarios and incurs lower communication overhead in several cases, offering an efficient, parameter-free primitive for majority consensus in resource-constrained environments.

Abstract

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.

Problem

• plurality consensus
• distributed systems
• simple agents
• opinion dynamics
• majority agreement

Innovation

• plurality consensus
• distributed systems
• DéjàVu
• communication efficiency
• repetition detection