An Improved Bound for the Beck-Fiala Conjecture

Fuente: arXiv
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Auteurs principaux: Bansal, Nikhil, Jiang, Haotian
Format: Preprint
Publié: 2025
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author Bansal, Nikhil
Jiang, Haotian
author_facet Bansal, Nikhil
Jiang, Haotian
contents In 1981, Beck and Fiala [Discrete Appl. Math, 1981] conjectured that given a set system $A \in \{0,1\}^{m \times n}$ with degree at most $k$ (i.e., each column of $A$ has at most $k$ non-zeros), its combinatorial discrepancy $\mathsf{disc}(A) := \min_{x \in \{\pm 1\}^n} \|Ax\|_\infty$ is at most $O(\sqrt{k})$. Previously, the best-known bounds for this conjecture were either $O(k)$, first established by Beck and Fiala [Discrete Appl. Math, 1981], or $O(\sqrt{k \log n})$, first proved by Banaszczyk [Random Struct. Algor., 1998]. We give an algorithmic proof of an improved bound of $O(\sqrt{k \log\log n})$ whenever $k \geq \log^5 n$, thus matching the Beck-Fiala conjecture up to $O(\sqrt{\log \log n})$ for almost the full regime of $k$.
format Preprint
id arxiv_https___arxiv_org_abs_2508_01937
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle An Improved Bound for the Beck-Fiala Conjecture
Bansal, Nikhil
Jiang, Haotian
Combinatorics
Discrete Mathematics
Data Structures and Algorithms
In 1981, Beck and Fiala [Discrete Appl. Math, 1981] conjectured that given a set system $A \in \{0,1\}^{m \times n}$ with degree at most $k$ (i.e., each column of $A$ has at most $k$ non-zeros), its combinatorial discrepancy $\mathsf{disc}(A) := \min_{x \in \{\pm 1\}^n} \|Ax\|_\infty$ is at most $O(\sqrt{k})$. Previously, the best-known bounds for this conjecture were either $O(k)$, first established by Beck and Fiala [Discrete Appl. Math, 1981], or $O(\sqrt{k \log n})$, first proved by Banaszczyk [Random Struct. Algor., 1998]. We give an algorithmic proof of an improved bound of $O(\sqrt{k \log\log n})$ whenever $k \geq \log^5 n$, thus matching the Beck-Fiala conjecture up to $O(\sqrt{\log \log n})$ for almost the full regime of $k$.
title An Improved Bound for the Beck-Fiala Conjecture
topic Combinatorics
Discrete Mathematics
Data Structures and Algorithms
url https://arxiv.org/abs/2508.01937