Sperner systems with restricted differences

Fuente: arXiv
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Autores principales: Xu, Zixiang, Yip, Chi Hoi
Formato: Preprint
Publicado: 2022
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author Xu, Zixiang
Yip, Chi Hoi
author_facet Xu, Zixiang
Yip, Chi Hoi
contents Let $\mathcal{F}$ be a family of subsets of $[n]$ and $L$ be a subset of $[n]$. We say $\mathcal{F}$ is an $L$-differencing Sperner system if $|A\setminus B|\in L$ for any distinct $A,B\in\mathcal{F}$. Let $p$ be a prime and $q$ be a power of $p$. Frankl first studied $p$-modular $L$-differencing Sperner systems and showed an upper bound of the form $\sum_{i=0}^{|L|}\binom{n}{i}$. In this paper, we obtain new upper bounds on $q$-modular $L$-differencing Sperner systems using elementary $p$-adic analysis and polynomial method, extending and improving existing results substantially. Moreover, our techniques can be used to derive new upper bounds on subsets of the hypercube with restricted Hamming distances. One highlight of the paper is the first analogue of the celebrated Snevily's theorem in the $q$-modular setting, which results in several new upper bounds on $q$-modular $L$-avoiding $L$-intersecting systems. In particular, we improve a result of Felszeghy, Hegedűs, and Rónyai, and give a partial answer to a question posed by Babai, Frankl, Kutin, and Štefankovič.
format Preprint
id arxiv_https___arxiv_org_abs_2210_02409
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Sperner systems with restricted differences
Xu, Zixiang
Yip, Chi Hoi
Combinatorics
Number Theory
05D05, 11B75
Let $\mathcal{F}$ be a family of subsets of $[n]$ and $L$ be a subset of $[n]$. We say $\mathcal{F}$ is an $L$-differencing Sperner system if $|A\setminus B|\in L$ for any distinct $A,B\in\mathcal{F}$. Let $p$ be a prime and $q$ be a power of $p$. Frankl first studied $p$-modular $L$-differencing Sperner systems and showed an upper bound of the form $\sum_{i=0}^{|L|}\binom{n}{i}$. In this paper, we obtain new upper bounds on $q$-modular $L$-differencing Sperner systems using elementary $p$-adic analysis and polynomial method, extending and improving existing results substantially. Moreover, our techniques can be used to derive new upper bounds on subsets of the hypercube with restricted Hamming distances. One highlight of the paper is the first analogue of the celebrated Snevily's theorem in the $q$-modular setting, which results in several new upper bounds on $q$-modular $L$-avoiding $L$-intersecting systems. In particular, we improve a result of Felszeghy, Hegedűs, and Rónyai, and give a partial answer to a question posed by Babai, Frankl, Kutin, and Štefankovič.
title Sperner systems with restricted differences
topic Combinatorics
Number Theory
05D05, 11B75
url https://arxiv.org/abs/2210.02409