The Assouad dimension of Kakeya sets in $\mathbb{R}^3$

Fuente: arXiv
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Main Authors: Wang, Hong, Zahl, Joshua
Format: Preprint
Published: 2024
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author Wang, Hong
Zahl, Joshua
author_facet Wang, Hong
Zahl, Joshua
contents This paper studies the structure of Kakeya sets in $\mathbb{R}^3$. We show that for every Kakeya set $K\subset\mathbb{R}^3$, there exist well-separated scales $0<δ<ρ\leq 1$ so that the $δ$ neighborhood of $K$ is almost as large as the $ρ$ neighborhood of $K$. As a consequence, every Kakeya set in $\mathbb{R}^3$ has Assouad dimension 3 and every Ahlfors-David regular Kakeya set in $\mathbb{R}^3$ has Hausdorff dimension 3. We also show that every Kakeya set in $\mathbb{R}^3$ that has "stably equal" Hausdorff and packing dimension (this is a new notion, which is introduced to avoid certain obvious obstructions) must have Hausdorff dimension 3. The above results follow from certain multi-scale structure theorems for arrangements of tubes and rectangular prisms in three dimensions, and a mild generalization of the sticky Kakeya theorem previously proved by the authors.
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id arxiv_https___arxiv_org_abs_2401_12337
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Assouad dimension of Kakeya sets in $\mathbb{R}^3$
Wang, Hong
Zahl, Joshua
Classical Analysis and ODEs
This paper studies the structure of Kakeya sets in $\mathbb{R}^3$. We show that for every Kakeya set $K\subset\mathbb{R}^3$, there exist well-separated scales $0<δ<ρ\leq 1$ so that the $δ$ neighborhood of $K$ is almost as large as the $ρ$ neighborhood of $K$. As a consequence, every Kakeya set in $\mathbb{R}^3$ has Assouad dimension 3 and every Ahlfors-David regular Kakeya set in $\mathbb{R}^3$ has Hausdorff dimension 3. We also show that every Kakeya set in $\mathbb{R}^3$ that has "stably equal" Hausdorff and packing dimension (this is a new notion, which is introduced to avoid certain obvious obstructions) must have Hausdorff dimension 3. The above results follow from certain multi-scale structure theorems for arrangements of tubes and rectangular prisms in three dimensions, and a mild generalization of the sticky Kakeya theorem previously proved by the authors.
title The Assouad dimension of Kakeya sets in $\mathbb{R}^3$
topic Classical Analysis and ODEs
url https://arxiv.org/abs/2401.12337