Arithmetic structure of the exceptional set of projections

Fuente: arXiv
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Main Authors: Chen, Changhao, Miao, Zhengyan
Format: Preprint
Published: 2022
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author Chen, Changhao
Miao, Zhengyan
author_facet Chen, Changhao
Miao, Zhengyan
contents We study the arithmetic structure of the exceptional set of projections. For any bounded subset $E\subset \mathbb{R}^d$, let $$ Ω=\{ξ\in \mathbb{R}: \dim_B(E+ξE)=\dim_B E\}. $$ We prove that either $Ω=\{0\}$ or $Ω$ is a subfield of $\mathbb{R}$. We show that in general the statement does not hold for Hausdorff dimension and lower box dimension. Moreover, for any $s\in (0, 1]$ and a sequence $(r_k) \subset \mathbb{R}$, we construct a Ahlfors $s$-regular set $E\subset \mathbb{R}^2$ such that for any $r_k, k\in \mathbb{N}$, we have \[ \overline{\dim}_B \, \{x+r_k\, y: (x, y)\in E\} <s. \]
format Preprint
id arxiv_https___arxiv_org_abs_2210_12677
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Arithmetic structure of the exceptional set of projections
Chen, Changhao
Miao, Zhengyan
Classical Analysis and ODEs
We study the arithmetic structure of the exceptional set of projections. For any bounded subset $E\subset \mathbb{R}^d$, let $$ Ω=\{ξ\in \mathbb{R}: \dim_B(E+ξE)=\dim_B E\}. $$ We prove that either $Ω=\{0\}$ or $Ω$ is a subfield of $\mathbb{R}$. We show that in general the statement does not hold for Hausdorff dimension and lower box dimension. Moreover, for any $s\in (0, 1]$ and a sequence $(r_k) \subset \mathbb{R}$, we construct a Ahlfors $s$-regular set $E\subset \mathbb{R}^2$ such that for any $r_k, k\in \mathbb{N}$, we have \[ \overline{\dim}_B \, \{x+r_k\, y: (x, y)\in E\} <s. \]
title Arithmetic structure of the exceptional set of projections
topic Classical Analysis and ODEs
url https://arxiv.org/abs/2210.12677