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Related papers: A Furstenberg-type problem for circles, and a Kauf…

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We prove the following restricted projection theorem. Let $n\ge 3$ and $\Sigma \subset S^{n}$ be an $(n-1)$-dimensional $C^2$ manifold such that $\Sigma$ has sectional curvature $>1$. Let $Z \subset \mathbb{R}^{n+1}$ be analytic and let $0…

Classical Analysis and ODEs · Mathematics 2023-12-08 Jiayin Liu

In this paper, we consider the so-called "Furstenberg set problem" in high dimensions. First, following Wolff's work on the two dimensional real case, we provide "reasonable" upper bounds for the problem for $\mathbb{R}$ or $\mathbb{F}_p$.…

Combinatorics · Mathematics 2019-02-20 Ruixiang Zhang

We consider the $L^p$ mapping properties of maximal averages associated to families of curves, and thickened curves, in the plane. These include the (planar) Kakeya maximal function, the circular maximal functions of Wolff and Bourgain, and…

Classical Analysis and ODEs · Mathematics 2025-10-09 Joshua Zahl

We generalize a Furstenberg-type result of Orponen-Shmerkin to higher dimensions, leading to an $\epsilon$-improvement in Kaufman's projection theorem for hyperplanes and an unconditional discretized radial projection theorem in the spirit…

Classical Analysis and ODEs · Mathematics 2023-09-11 Kevin Ren

We fully resolve the Furstenberg set conjecture in $\mathbb{R}^2$, that a $(s, t)$-Furstenberg set has Hausdorff dimension $\ge \min(s+t, \frac{3s+t}{2}, s+1)$. As a result, we obtain an analogue of Elekes' bound for the discretized…

Classical Analysis and ODEs · Mathematics 2025-01-22 Kevin Ren , Hong Wang

In 1997, Thomas Wolff proved sharp $L^3$ bounds for his circular maximal function, and in 1999, Kolasa and Wolff proved certain non-sharp $L^p$ inequalities for a broader class of maximal functions arising from curves of the form…

Classical Analysis and ODEs · Mathematics 2013-08-05 Joshua Zahl

In this paper we come up with a dual version of the Furstenberg problem and obtain partial results via $L^p$ estimates of orthogonal projections. Examples are also discussed. Moreover, compared with general sets, we find that special…

Classical Analysis and ODEs · Mathematics 2024-12-10 Longhui Li , Bochen Liu

We prove sharp $L^3$ bounds for a variable coefficient generalization of the Wolff circular maximal function $M^\delta f$. For each fixed radius $r$, $M^\delta f(r)$ is the maximal average of $f$ over the $\delta$--neighborhood of a circle…

Classical Analysis and ODEs · Mathematics 2018-07-18 Joshua Zahl

We generalize the Fenchel theorem to strong spacelike (which means that the tangent vector and the curvature vector span a spacelike 2-plane at each point) closed curves with index 1 in the 3-dimensional Lorentz space, showing that the…

Differential Geometry · Mathematics 2016-03-07 Nan Ye , Xiang Ma , Donghao Wang

We consider the problem of bounding the number of exceptional projections (projections which are smaller than typical) of a subset of a vector space over a finite field onto subspaces. We establish bounds that depend on $L^p$ estimates for…

Combinatorics · Mathematics 2025-04-24 Jonathan M. Fraser , Firdavs Rakhmonov

In this paper, we study in prime fields the exceptional set estimates, which can be viewed as a refinement of Marstrand's orthogonal projection theorem. Additionally, we address a Furstenberg-type problem, which is closely related. It is…

Classical Analysis and ODEs · Mathematics 2025-09-30 Shengwen Gan

Recently Wolff obtained a nearly sharp $L^2$ bilinear restriction theorem for bounded subsets of the cone in general dimension. We obtain the endpoint of Wolff's estimate and generalize to the case when one of the subsets is large. As a…

Classical Analysis and ODEs · Mathematics 2007-05-23 Terence Tao

This article is a study guide for ``On the Hausdorff dimension of Furstenberg sets and orthogonal projections in the plane" by Orponen and Shmerkin. We begin by introducing Furstenberg set problem and exceptional set of projections and…

Classical Analysis and ODEs · Mathematics 2024-06-10 Jacob B. Fiedler , Guo-Dong Hong , Donggeun Ryou , Shukun Wu

The problem of $L^p(R^3)\to L^2(S)$ Fourier restriction estimates for smooth hypersurfaces S of finite type in R^3 is by now very well understood for a large class of hypersurfaces, including all analytic ones. In this article, we take up…

Classical Analysis and ODEs · Mathematics 2017-06-14 Stefan Buschenhenke , Detlef Müller , Ana Vargas

We propose to study the restriction conjecture using decoupling theorems and two-ends Furstenberg inequalities. Specifically, we pose a two-ends Furstenberg conjecture, which implies the restriction conjecture. As evidence, we prove this…

Classical Analysis and ODEs · Mathematics 2024-12-20 Hong Wang , Shukun Wu

We consider certain estimates involving averaging operators over curves and hypersurfaces that can be cast into a combinatorial framework. We show that hypersurfaces with nonzero rotational curvature satisfy the usual restricted weak-type…

Classical Analysis and ODEs · Mathematics 2007-05-23 W. Schlag

We provide exposition into the field of projection theory, which lies at the intersection of incidence geometry and geometric measure theory. We first give the necessary preliminaries in Chapter 2, focusing on incidences between points and…

Classical Analysis and ODEs · Mathematics 2025-09-30 Paige Bright

Let $0 \leq s \leq 1$. A set $K \subset \mathbb{R}^{2}$ is a Furstenberg $s$-set, if for every unit vector $e \in S^{1}$, some line $L_{e}$ parallel to $e$ satisfies $$\dim_{\mathrm{H}} [K \cap L_{e}] \geq s.$$ The Furstenberg set problem,…

Classical Analysis and ODEs · Mathematics 2017-09-25 Tuomas Orponen

We make progress on two interrelated problems at the intersection of geometric measure theory, additive combinatorics and harmonic analysis: the discretised sum-product problem, and the dimension of Furstenberg sets. Along the way, we…

Classical Analysis and ODEs · Mathematics 2026-03-24 Tuomas Orponen , Pablo Shmerkin

Using some resolution of singularities and oscillatory integral methods in conjunction with appropriate damping and interpolation techniques, L^p boundedness theorems for p > 2 are obtained for maximal operators over a wide range of…

Classical Analysis and ODEs · Mathematics 2010-02-07 Michael Greenblatt
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