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Related papers: On the Dimension of Kakeya Sets in the First Heise…

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We consider (bounded) Besicovitch sets in the Heisenberg group and prove that $L^p$ estimates for the Kakeya maximal function imply lower bounds for their Heisenberg Hausdorff dimension.

Metric Geometry · Mathematics 2017-03-13 Laura Venieri

In this dissertation we define a generalization of Kakeya sets in certain metric spaces. Kakeya sets in Euclidean spaces are sets of zero Lebesgue measure containing a segment of length one in every direction. A famous conjecture, known as…

Classical Analysis and ODEs · Mathematics 2017-03-13 Laura Venieri

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 $0<\delta<\rho\leq 1$ so that the $\delta$ neighborhood of $K$ is almost as large…

Classical Analysis and ODEs · Mathematics 2025-05-07 Hong Wang , Joshua Zahl

A Kakeya set in $\mathbb{R}^n$ is a compact set that contains a unit line segment $I_e$ in each direction $e \in S^{n-1}$. The Kakeya conjecture states that any Kakeya set in $\mathbb{R}^n$ has Hausdorff dimension $n$. We consider a…

Classical Analysis and ODEs · Mathematics 2025-06-26 Jonathan M. Fraser , Lijian Yang

Katz and Zahl used a planebrush argument to prove that Kakeya sets in $\mathbb{R}^4$ have Hausdorff dimension at least 3.059. In the special case when the Kakeya set is plany, their argument gives a better lower bound of 10/3. We give a…

Classical Analysis and ODEs · Mathematics 2026-01-13 Izabella Łaba , Mukul Rai Choudhuri , Joshua Zahl

Kakeya sets are compact subsets of $\mathbb{R}^n$ that contain a unit line segment pointing in every direction. The Kakeya conjecture states that such sets must have Hausdorff dimension $n$. The property of stickiness was first discovered…

Classical Analysis and ODEs · Mathematics 2024-11-01 Mukul Rai Choudhuri

We consider unions of $SL(2)$ lines in $\mathbb{R}^{3}$. These are lines of the form $$L = (a,b,0) + \mathrm{span}(c,d,1),$$ where $ad - bc = 1$. We show that if $\mathcal{L}$ is a Kakeya set of $SL(2)$ lines, then the union $\cup…

Classical Analysis and ODEs · Mathematics 2022-10-19 Katrin Fässler , Tuomas Orponen

We prove that every Kakeya set in $\mathbb{R}^3$ formed from lines of the form $(a,b,0) + \operatorname{span}(c,d,1)$ with $ad-bc=1$ must have Hausdorff dimension $3$; Kakeya sets of this type are called $SL_2$ Kakeya sets. This result was…

Classical Analysis and ODEs · Mathematics 2023-08-17 Nets Hawk Katz , Shukun Wu , Joshua Zahl

A Kakeya set is a compact subset of $\mathbb{R}^n$ that contains a unit line segment pointing in every direction. The Kakeya conjecture asserts that such sets must have Hausdorff and Minkowski dimension $n$. There is a special class of…

Classical Analysis and ODEs · Mathematics 2025-12-09 Hong Wang , Joshua Zahl

An improved a.e. lower bound is given for Hausdorff dimension under vertical projections in the first Heisenberg group.

Classical Analysis and ODEs · Mathematics 2020-08-25 Terence L. J. Harris

We define the Heisenberg Kakeya maximal functions $M_{\delta}f$, $0<\delta<1$, by averaging over $\delta$-neighborhoods of horizontal unit line segments in the Heisenberg group $\mathbb{H}^1$ equipped with the Kor\'{a}nyi distance…

Classical Analysis and ODEs · Mathematics 2023-11-28 Katrin Fässler , Andrea Pinamonti , Pietro Wald

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…

Classical Analysis and ODEs · Mathematics 2026-05-22 Jonathan M. Fraser , Lijian Yang

Here we show some results related with Kakeya conjecture which says that for any integer $n\geq 2$, a set containing line segments in every dimension in $\mathbb{R}^n$ has full Hausdorff dimension as well as box dimension. We proved here…

Classical Analysis and ODEs · Mathematics 2017-04-17 Han Yu

We prove that the Kakeya maximal conjecture is equivalent to the $\Omega$-Kakeya maximal conjecture. This completes a recent result in [2] where Keleti and Math{\'e} proved that the Kakeya conjecture is equivalent to the $\Omega$-Kakeya…

Classical Analysis and ODEs · Mathematics 2022-04-05 Anthony Gauvan

It is shown that if $A$ is a Borel subset of the first Heisenberg group, with Hausdorff dimension satisfying $2< \dim A < 3$, then the packing dimensions of vertical projections of $A$ are almost surely not less than $\dim A$, where both…

Classical Analysis and ODEs · Mathematics 2026-03-10 Terence L. J. Harris

We study sets of $\delta$ tubes in $\mathbb{R}^3$, with the property that not too many tubes can be contained inside a common convex set $V$. We show that the union of tubes from such a set must have almost maximal volume. As a consequence,…

Classical Analysis and ODEs · Mathematics 2025-02-26 Hong Wang , Joshua Zahl

A Kakeya set is a subset of F^n, where F is a finite field of q elements, that contains a line in every direction. In this paper we show that the size of every Kakeya set is at least C_n * q^n, where C_n depends only on n. This improves the…

Combinatorics · Mathematics 2015-05-13 Zeev Dvir

It is shown that vertical projections in the Heisenberg group of sets of dimension strictly greater than 3 almost surely have positive area. The proof uses the point-plate incidence method introduced by F\"assler and Orponen, and also uses…

Classical Analysis and ODEs · Mathematics 2025-09-03 Terence L. J. Harris

We prove some geometric properties of sets in the first Heisenberg group whose Heisenberg Hausdorff dimension is the minimal or maximal possible in relation to their Euclidean one and the corresponding Hausdorff measures are positive and…

Classical Analysis and ODEs · Mathematics 2017-05-12 Pertti Mattila , Laura Venieri

A Kakeya set $\mathcal{K}$ in an affine plane of order $q$ is the point set covered by a set $\mathcal{L}$ of $q+1$ pairwise non-parallel lines. Large Kakeya sets were studied by Dover and Mellinger; in [6] they showed that Kakeya sets with…

Combinatorics · Mathematics 2020-03-20 Maarten De Boeck , Geertrui Van de Voorde
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