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This work focuses on an improved fractional Sobolev inequality with a remainder term involving the Hardy-Littlewood-Sobolev inequality which has been proved recently. By extending a recent result on the standard Laplacian to the fractional…

Functional Analysis · Mathematics 2014-07-16 Gaspard Jankowiak , Van Hoang Nguyen

This is the first in our series of papers concerning some Hardy-Littlewood-Sobolev type inequalities. In the present paper, the main objective is to establish the following sharp reversed HLS inequality in the whole space $\mathbb R^n$…

Analysis of PDEs · Mathematics 2018-08-31 Quôc-Anh Ngô , Van Hoang Nguyen

This note presents a method based on Feynman-Kac semigroups for logarithmic Sobolev inequalities. It follows the recent work of Bonnefont and Joulin on intertwining relations for diffusion operators, formerly used for spectral gap…

Functional Analysis · Mathematics 2021-06-09 Clément Steiner

For metric measure spaces verifying the reduced curvature-dimension condition $CD^*(K,N)$ we prove a series of sharp functional inequalities under the additional assumption of essentially non-branching. Examples of spaces entering this…

Metric Geometry · Mathematics 2019-05-08 Fabio Cavalletti , Andrea Mondino

We prove all the maximizers of the sharp Hardy-Littlewood-Sobolev inequality are smooth. More generally, we show all the nonnegative critical functions are smooth, radial with respect to some points and strictly decreasing in the radial…

Analysis of PDEs · Mathematics 2007-05-23 Fengbo Hang

We obtain an improved Sobolev inequality in H^s spaces involving Morrey norms. This refinement yields a direct proof of the existence of optimizers and the compactness up to symmetry of optimizing sequences for the usual Sobolev embedding.…

Analysis of PDEs · Mathematics 2013-02-26 Giampiero Palatucci , Adriano Pisante

We prove sharp inequalities of Hardy type for functions in the Sobolev space $W^{1,p}$ on the unit sphere $\mathbb{S}^{n-1}$ in $\mathbb{R}^{n}$. We achieve this in both the subcritical and critical cases. The method we use to show…

Functional Analysis · Mathematics 2020-06-15 Ahmed A. Abdelhakim

In this note we prove two isoperimetric inequalities for the sharp constant in the Sobolev embedding and its associated extremal function. The first such inequality is a variation on the classical Schwarz Lemma from complex analysis,…

Analysis of PDEs · Mathematics 2016-02-02 Tom Carroll , Jesse Ratzkin

We give the full solution of the following problem: obtain sharp inequalities between the moduli of smoothness $\omega_\alpha(f,t)_q$ and $\omega_\beta(f,t)_p$ for $0<p<q\le \infty$. A similar problem for the generalized $K$-functionals and…

Classical Analysis and ODEs · Mathematics 2017-11-23 Yurii Kolomoitsev , Sergey Tikhonov

Sharp affine fractional Sobolev inequalities for functions on $\mathbb R^n$ are established. For each $0<s<1$, the new inequalities are significantly stronger than (and directly imply) the sharp fractional Sobolev inequalities of Almgren…

Metric Geometry · Mathematics 2025-09-30 Julián Haddad , Monika Ludwig

A novel representation is developed as a measure for multilinear fractional embedding. Corresponding extensions are given for the Bourgain-Brezis-Mironescu theorem and Pitt's inequality. New results are obtained for diagonal trace…

Analysis of PDEs · Mathematics 2014-06-06 William Beckner

We derive sharp Sobolev embeddings on a class of Sobolev spaces with potential weights without assuming any boundary conditions. Moreover, we consider the Adams-type inequalities for the borderline Sobolev embedding into the exponential…

Analysis of PDEs · Mathematics 2024-10-24 João Marcos do Ó , Guozhen Lu , Raoní Ponciano

For a function $f$ from the Sobolev space $W^{1,p}(C)$ ($C\subset\mathbb{R}^d$ is an open convex cone), a sharp inequality that estimates $\| f\|_{L_{\infty}}$ via the $L_{p}$-norm of its gradient and a seminorm of the function is obtained.…

Functional Analysis · Mathematics 2025-03-18 V. F. Babenko , V. V. Babenko , O. V. Kovalenko , N. V. Parfinovych

For $n > k \geq 0$, $\lambda >0$, and $p, r>1$, we establish the following optimal Hardy-Littlewood-Sobolev inequality \[ \Big| \iint_{\mathbf R^n \times \mathbf R^{n-k}} \frac{f(x) g(y)}{ |x-y|^\lambda |y"|^\beta} dx dy \Big| \lesssim \| f…

Functional Analysis · Mathematics 2026-03-17 Quôc Anh Ngô , Quoc-Hung Nguyen , Van Hoang Nguyen

We derive sharp Sobolev inequalities for Sobolev spaces on metric spaces. In particular, we obtain new sharp Sobolev embeddings and Faber-Krahn estimates for H\"{o}rmander vector fields.

Functional Analysis · Mathematics 2008-06-03 Jan Kalis , Mario Milman

Assume that $M$ is a CR compact manifold without boundary and CR Yamabe invariant $\mathcal{Y}(M)$ is positive. Here, we devote to study a class of sharp Hardy-Littlewood-Sobolev inequality as follows \begin{equation*} \Bigl| \int_M\int_M…

Analysis of PDEs · Mathematics 2021-06-15 Yazhou Han

We establish a sharp Adams-type inequality invoking a Hardy inequality for any even dimension. This leads to a non compact Sobolev embedding in some Orlicz space. We also give a description of the lack of compactness of this embedding in…

Analysis of PDEs · Mathematics 2015-02-19 Mohamed Khalil Zghal

We investigate asymptotically sharp upper and lower bounds for the approximation numbers of the compact Sobolev embeddings $\overset{\circ}{W}{^m}(\Omega)\hookrightarrow L_2(\Omega)$ and $ W^m(\Omega)\hookrightarrow L_2(\Omega)$, defined on…

Functional Analysis · Mathematics 2018-11-06 Therese Mieth

The paper is devoted to proving Allard-Michael-Simon-type $L^p$-Sobolev inequalities $(p>1)$ with explicit constants in the setting of Euclidean minimal submanifolds of arbitrary codimension. Our results require separate discussions for the…

Analysis of PDEs · Mathematics 2026-03-09 Zoltán M. Balogh , Alexandru Kristály , Ágnes Mester

We classify local minimizers of $\int\sigma_2+\oint H_2$ among all conformally flat metrics in the Euclidean $(n+1)$-ball, $4\leq n\leq 5$, for which the boundary has unit volume, subject to an ellipticity assumption. We also classify local…

Analysis of PDEs · Mathematics 2019-11-01 Jeffrey S. Case , Yi Wang