Bohr recurrence and density of non-lacunary semigroups of $\mathbb{N}$

Fuente: arXiv
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Autori principali: Frantzikinakis, Nikos, Host, Bernard, Kra, Bryna
Natura: Preprint
Pubblicazione: 2024
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author Frantzikinakis, Nikos
Host, Bernard
Kra, Bryna
author_facet Frantzikinakis, Nikos
Host, Bernard
Kra, Bryna
contents A subset $R$ of integers is a set of Bohr recurrence if every rotation on $\mathbb{T}^d$ returns arbitrarily close to zero under some non-zero multiple of $R$. We show that the set $\{k!\, 2^m3^n\colon k,m,n\in \mathbb{N}\}$ is a set of Bohr recurrence. This is a particular case of a more general statement about images of such sets under any integer polynomial with zero constant term. We also show that if $P$ is a real polynomial with at least one non-constant irrational coefficient, then the set $\{P(2^m3^n)\colon m,n\in \mathbb{N}\}$ is dense in $\mathbb{T}$, thus providing a joint generalization of two well-known results, one of Furstenberg and one of Weyl.
format Preprint
id arxiv_https___arxiv_org_abs_2406_01353
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Bohr recurrence and density of non-lacunary semigroups of $\mathbb{N}$
Frantzikinakis, Nikos
Host, Bernard
Kra, Bryna
Dynamical Systems
Combinatorics
Primary: 37B20, Secondary: 37A44, 37C85, 11J71, 05B10
A subset $R$ of integers is a set of Bohr recurrence if every rotation on $\mathbb{T}^d$ returns arbitrarily close to zero under some non-zero multiple of $R$. We show that the set $\{k!\, 2^m3^n\colon k,m,n\in \mathbb{N}\}$ is a set of Bohr recurrence. This is a particular case of a more general statement about images of such sets under any integer polynomial with zero constant term. We also show that if $P$ is a real polynomial with at least one non-constant irrational coefficient, then the set $\{P(2^m3^n)\colon m,n\in \mathbb{N}\}$ is dense in $\mathbb{T}$, thus providing a joint generalization of two well-known results, one of Furstenberg and one of Weyl.
title Bohr recurrence and density of non-lacunary semigroups of $\mathbb{N}$
topic Dynamical Systems
Combinatorics
Primary: 37B20, Secondary: 37A44, 37C85, 11J71, 05B10
url https://arxiv.org/abs/2406.01353