Fourier analytic variants of the Furstenberg and Kakeya problems

Fuente: arXiv
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Auteurs principaux: Fraser, Jonathan M., Yang, Lijian
Format: Preprint
Publié: 2026
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author Fraser, Jonathan M.
Yang, Lijian
author_facet Fraser, Jonathan M.
Yang, Lijian
contents We study several distinct but related Fourier analytic variants of the well-known Kakeya and Furstenberg set problems in the plane. For example, given $0<s,t<1$, we call a set $K \subseteq \mathbb{R}^2$ an $(s,t)$-Kakeya set if there exists a set of directions $E \subseteq S^1$ with Hausdorff dimension at least $t$ such that, for each $e \in E$, the set $K$ contains a subset of a unit line segment in direction $e$ whose Fourier dimension, viewed as a subset of $\mathbb{R}$, is at least $s$. For $Δ(s,t)$ defined to be the infimum of the Fourier dimension among all $(s,t)$-Kakeya sets in $\mathbb{R}^2$, we prove that \[ \frac{2st}{s+2t} \leq Δ(s,t) \leq \min\{s,2t\}. \] These bounds, though distinct, are asymptotically equivalent as either $s$ or $t$ tends to zero. We also obtain upper and lower bounds in the Furstenberg set version of the problem and in the case where the Hausdorff dimension of the collection of lines is replaced by the Fourier dimension.
format Preprint
id arxiv_https___arxiv_org_abs_2605_21668
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Fourier analytic variants of the Furstenberg and Kakeya problems
Fraser, Jonathan M.
Yang, Lijian
Classical Analysis and ODEs
Metric Geometry
We study several distinct but related Fourier analytic variants of the well-known Kakeya and Furstenberg set problems in the plane. For example, given $0<s,t<1$, we call a set $K \subseteq \mathbb{R}^2$ an $(s,t)$-Kakeya set if there exists a set of directions $E \subseteq S^1$ with Hausdorff dimension at least $t$ such that, for each $e \in E$, the set $K$ contains a subset of a unit line segment in direction $e$ whose Fourier dimension, viewed as a subset of $\mathbb{R}$, is at least $s$. For $Δ(s,t)$ defined to be the infimum of the Fourier dimension among all $(s,t)$-Kakeya sets in $\mathbb{R}^2$, we prove that \[ \frac{2st}{s+2t} \leq Δ(s,t) \leq \min\{s,2t\}. \] These bounds, though distinct, are asymptotically equivalent as either $s$ or $t$ tends to zero. We also obtain upper and lower bounds in the Furstenberg set version of the problem and in the case where the Hausdorff dimension of the collection of lines is replaced by the Fourier dimension.
title Fourier analytic variants of the Furstenberg and Kakeya problems
topic Classical Analysis and ODEs
Metric Geometry
url https://arxiv.org/abs/2605.21668