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We establish a sharp adjoint Fourier restriction inequality for the end-point Tomas-Stein restriction theorem on the circle under a certain arithmetic constraint on the support set of the Fourier coefficients of the given function. Such…

Classical Analysis and ODEs · Mathematics 2024-02-15 Valentina Ciccone , Felipe Gonçalves

In this paper we prove a sharp trilinear inequality which is motivated by a program to obtain the sharp form of the $L^2 - L^6$ Tomas-Stein adjoint restriction inequality on the circle. Our method uses intricate estimates for integrals of…

Classical Analysis and ODEs · Mathematics 2021-09-30 Emanuel Carneiro , Damiano Foschi , Diogo Oliveira e Silva , Christoph Thiele

We prove a sharp Fourier extension inequality on the circle for the Tomas-Stein exponent for functions whose spectrum $\{\pm \lambda_n\}$ satisfies $\lambda_{n+1}>3 \lambda_{n}$.

Classical Analysis and ODEs · Mathematics 2025-10-27 Felipe Gonçalves , João Paulo Ferreira

Among the class of functions on the circle with Fourier modes up to degree 120, constant functions are the unique real-valued maximizers for the endpoint Tomas-Stein inequality.

Classical Analysis and ODEs · Mathematics 2022-03-07 James Barker , Christoph Thiele , Pavel Zorin-Kranich

Sharp restriction theory and the finite field extension problem have both received a great deal of attention in the last two decades, but so far they have not intersected. In this paper, we initiate the study of sharp restriction theory on…

Classical Analysis and ODEs · Mathematics 2024-07-15 Cristian González-Riquelme , Diogo Oliveira e Silva

In this note, we study maximizers for Fourier extension inequalities on the sphere. We prove that constant functions are local maximizers for the $L^p(\mathbb{S}^{d-1})$ to $L^p(\mathbb{R}^d)$ Fourier extension estimates in the same range…

Classical Analysis and ODEs · Mathematics 2025-09-03 Valentina Ciccone , Mateus Sousa

Among the class of functions with Fourier modes up to degree 30, constant functions are the unique real-valued maximizers for the endpoint Tomas-Stein inequality on the circle.

Classical Analysis and ODEs · Mathematics 2022-01-04 Diogo Oliveira e Silva , Christoph Thiele , Pavel Zorin-Kranich

The adjoint Fourier restriction inequality of Tomas and Stein states that the mapping $f\mapsto \widehat{f\sigma}$ is bounded from $\lt(S^2)$ to $L^4(\reals^3)$. We prove that there exist functions which extremize this inequality, and that…

Classical Analysis and ODEs · Mathematics 2010-06-23 Michael Christ , Shuanglin Shao

We show that, possibly after a compactification of spacetime, constant functions are local maximizers of the Tomas-Stein adjoint Fourier restriction inequality for the cone and paraboloid in every dimension, and for the sphere in dimension…

Classical Analysis and ODEs · Mathematics 2022-09-14 Felipe Gonçalves , Giuseppe Negro

In this article, we prove some total variation inequalities for maximal functions. Our results deal with two possible generalizations of the results contained in Aldaz and P\'erez L\'azaro's work, one of whose considers a variable…

Classical Analysis and ODEs · Mathematics 2018-01-31 João Pedro Ramos

We prove sharp estimates for Fourier transforms of indicator functions of bounded open sets in ${\mathbb R}^n$ with real analytic boundary, as well as nontrivial lattice point discrepancy results. Both will be derived from estimates on…

Classical Analysis and ODEs · Mathematics 2021-01-19 Michael Greenblatt

We prove that constant functions are the unique real-valued maximizers for all $L^2-L^{2n}$ adjoint Fourier restriction inequalities on the unit sphere $\mathbb{S}^{d-1}\subset\mathbb{R}^d$, $d\in\{3,4,5,6,7\}$, where $n\geq 3$ is an…

Classical Analysis and ODEs · Mathematics 2021-01-11 Diogo Oliveira e Silva , René Quilodrán

We prove a new family of sharp $L^2(\mathbb S^{d-1})\to L^4(\mathbb R^d)$ Fourier extension inequalities from the unit sphere $\mathbb S^{d-1}\subset \mathbb R^d$, valid in arbitrary dimensions $d\geq 3$.

Classical Analysis and ODEs · Mathematics 2025-03-19 Emanuel Carneiro , Giuseppe Negro , Diogo Oliveira e Silva

The adjoint Fourier restriction inequality for the sphere $S^2$ states that if $f\in\lt(S^2,\sigma)$ then $\widehat{f\sigma}\in L^4(\reals^3)$. We prove that all critical points $f$ of the functional…

Classical Analysis and ODEs · Mathematics 2010-06-23 Michael Christ , Shuanglin Shao

We show that constant functions are global maximizers for the adjoint Fourier restriction inequality for the sphere.

Classical Analysis and ODEs · Mathematics 2014-10-23 Damiano Foschi

In dimensions $d \in \{3,4,5,6,7\}$, we prove that the constant functions on the unit sphere $\mathbb{S}^{d-1}\subset \mathbb{R}^d$ maximize the weighted adjoint Fourier restriction inequality $$ \left| \int_{\mathbb{R}^d}…

Classical Analysis and ODEs · Mathematics 2024-10-15 Emanuel Carneiro , Giuseppe Negro , Diogo Oliveira e Silva

For $\alpha\geq 2$, we investigate a class of Fourier extension operators on fractional surfaces $(\xi,|\xi|^\alpha)$. For the corresponding $\alpha$-Strichartz inequalities, by applying the missing mass method and bilinear restriction…

Classical Analysis and ODEs · Mathematics 2024-07-02 Boning Di , Dunyan Yan

We study the symmetry/asymmetry of functions providing sharp constants in the embedding theorems ${\stackrel{\circ}{W}}\vphantom{W}_2^r(-1,1)\hookrightarrow{\stackrel{\circ}{W}}\vphantom{W}_\infty^k(-1,1)$ for various $r$ and $k$. The sharp…

Classical Analysis and ODEs · Mathematics 2014-08-19 E. V. Mukoseeva , A. I. Nazarov

We give a proof of Fourier extension conjecture on the paraboloid in all dimensions bigger than 2 that begins with a decomposition suggested in Sawyer [Saw8] of writing a smooth Alpert projection as a sum of pieces whose Fourier extensions…

Classical Analysis and ODEs · Mathematics 2026-05-19 Cristian Rios , Eric T. Sawyer

The inverse tangent function can be bounded by different inequalities, for example by Shafer's inequality. In this publication, we propose a new sharp double inequality, consisting of a lower and an upper bound, for the inverse tangent…

Information Theory · Computer Science 2013-07-19 Gholamreza Alirezaei
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