Core-Halo Decomposition: Decentralizing Large-Scale Fixed-Point Problems

Fuente: arXiv
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Main Authors: Haixiang, Xu, Yang, Zhang, Jiefu, Wu, Xudong, Zhou, Zihan, He, Jun, Chen, Jiayu
Format: Preprint
Published: 2026
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author Haixiang
Xu, Yang
Zhang, Jiefu
Wu, Xudong
Zhou, Zihan
He, Jun
Chen, Jiayu
author_facet Haixiang
Xu, Yang
Zhang, Jiefu
Wu, Xudong
Zhou, Zihan
He, Jun
Chen, Jiayu
contents We study solving large-scale fixed-point equation \(x^\star=\bar F(x^\star)\) with decomposition. Standard strict decomposition assigns each agent a disjoint block and evaluates updates using only owned coordinates. For most operators, however, a block update may depend on variables outside the block. Truncating these dependencies by strict decomposition changes the mean operator and creates structural bias that cannot be removed by more samples, smaller stepsizes, or additional consensus. We therefore propose Core-Halo decomposition, which separates write ownership from read-only evaluation context: each agent updates its own core and reads from an overlapping halo. By aligning the Core-Halo decomposition with the block-dependence structure of $\bar F$, the original fixed-point problem can be implemented faithfully in a decentralized multi-agent system. We further characterize the fundamental obstruction faced by strict decomposition through a Bellman closure condition and a blockwise bias lower bound, showing that local-only updates can alter the original fixed-point operator. Finally, we conduct extensive experiments across a range of application settings, and demonstrate that Core-Halo achieves near-centralized performance while retaining the parallelism benefits of decentralization.
format Preprint
id arxiv_https___arxiv_org_abs_2605_08681
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Core-Halo Decomposition: Decentralizing Large-Scale Fixed-Point Problems
Haixiang
Xu, Yang
Zhang, Jiefu
Wu, Xudong
Zhou, Zihan
He, Jun
Chen, Jiayu
Machine Learning
Artificial Intelligence
Numerical Analysis
We study solving large-scale fixed-point equation \(x^\star=\bar F(x^\star)\) with decomposition. Standard strict decomposition assigns each agent a disjoint block and evaluates updates using only owned coordinates. For most operators, however, a block update may depend on variables outside the block. Truncating these dependencies by strict decomposition changes the mean operator and creates structural bias that cannot be removed by more samples, smaller stepsizes, or additional consensus. We therefore propose Core-Halo decomposition, which separates write ownership from read-only evaluation context: each agent updates its own core and reads from an overlapping halo. By aligning the Core-Halo decomposition with the block-dependence structure of $\bar F$, the original fixed-point problem can be implemented faithfully in a decentralized multi-agent system. We further characterize the fundamental obstruction faced by strict decomposition through a Bellman closure condition and a blockwise bias lower bound, showing that local-only updates can alter the original fixed-point operator. Finally, we conduct extensive experiments across a range of application settings, and demonstrate that Core-Halo achieves near-centralized performance while retaining the parallelism benefits of decentralization.
title Core-Halo Decomposition: Decentralizing Large-Scale Fixed-Point Problems
topic Machine Learning
Artificial Intelligence
Numerical Analysis
url https://arxiv.org/abs/2605.08681