A note on the largest sum-free sets of integers

Fuente: arXiv
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Main Authors: Jing, Yifan, Wu, Shukun
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Published: 2020
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author Jing, Yifan
Wu, Shukun
author_facet Jing, Yifan
Wu, Shukun
contents Given $A$ a set of $N$ positive integers, an old question in additive combinatorics asks that whether $A$ contains a sum-free subset of size at least $N/3+ω(N)$ for some increasing unbounded function $ω$. The question is generally attacked in the literature by considering another conjecture, which asserts that as $N\to\infty$, $\max_{x\in\mathbb{R}/\mathbb{Z}}\sum_{n\in A}({\bf 1}_{(1/3,2/3)}-1/3)(nx)\to\infty$. This conjecture, if true, would also imply that a similar phenomenon occurs for $(2k,4k)$-sum-free sets for every $k\geq1$. In this note, we prove the latter result directly. The new ingredient of our proof is a structural analysis on the host set $A$, which might be of independent interest.
format Preprint
id arxiv_https___arxiv_org_abs_2011_09963
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle A note on the largest sum-free sets of integers
Jing, Yifan
Wu, Shukun
Combinatorics
Classical Analysis and ODEs
Number Theory
11B30, 11K70, 05D10
Given $A$ a set of $N$ positive integers, an old question in additive combinatorics asks that whether $A$ contains a sum-free subset of size at least $N/3+ω(N)$ for some increasing unbounded function $ω$. The question is generally attacked in the literature by considering another conjecture, which asserts that as $N\to\infty$, $\max_{x\in\mathbb{R}/\mathbb{Z}}\sum_{n\in A}({\bf 1}_{(1/3,2/3)}-1/3)(nx)\to\infty$. This conjecture, if true, would also imply that a similar phenomenon occurs for $(2k,4k)$-sum-free sets for every $k\geq1$. In this note, we prove the latter result directly. The new ingredient of our proof is a structural analysis on the host set $A$, which might be of independent interest.
title A note on the largest sum-free sets of integers
topic Combinatorics
Classical Analysis and ODEs
Number Theory
11B30, 11K70, 05D10
url https://arxiv.org/abs/2011.09963