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arXiv · 2301.06750

Sum-free sets in $Z_5^n$

Vsevolod F. Lev
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Abstract

It is well-known that for a prime $p\equiv 2\pmod 3$ and integer $n\ge 1$, the maximum possible size of a sum-free subset of the elementary abelian group $\mathbb Z_p^n$ is $\frac13\,(p+1)p^{n-1}$. We establish a matching stability result in the case $p=5$: if $A\subseteq\mathbb Z_5^n$ is a sum-free subset of size $|A|>\frac32\cdot5^{n-1}$, then there are a subgroup $H<\mathbb Z_5^n$ of size $|H|=5^{n-1}$ and an element $e\notin H$ such that $A\subseteq(e+H)\cup(-e+H)$.

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Vsevolod F. Lev. 2023-01-17. Sum-free sets in $Z_5^n$. https://arxiv.org/abs/2301.06750

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