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We establish an analog Hardy inequality with sharp constant involving exponential weight function. The special case of this inequality (for n=2) leads to a direct proof of Onofri inequality on S^2.

Analysis of PDEs · Mathematics 2007-10-24 Suyu Li , Meijun Zhu

We study the sharp doubling inequalities for the gradients and upper bounds for the critical sets of Dirichlet eigenfunctions on the boundary and in the interior of compact Riemannian manifolds. Most efforts are devoted to obtaining the…

Analysis of PDEs · Mathematics 2020-10-12 Jiuyi Zhu

In 2004, J.C. Tong found bounds for the approximation quality of a regular continued fraction convergent of a rational number, expressed in bounds for both the previous and next approximation. We sharpen his results with a geometric method…

Number Theory · Mathematics 2009-08-25 Cor Kraaikamp , Ionica Smeets

We give a partial negative answer to a question left open in a previous work by Brasco and the first and third-named authors concerning the sharp constant in the fractional Hardy inequality on convex sets. Our approach has a geometrical…

Analysis of PDEs · Mathematics 2025-09-30 Francesca Bianchi , Giorgio Stefani , Anna Chiara Zagati

In this paper we characterize sharp time-data tradeoffs for optimization problems used for solving linear inverse problems. We focus on the minimization of a least-squares objective subject to a constraint defined as the sub-level set of a…

Information Theory · Computer Science 2016-01-06 Samet Oymak , Benjamin Recht , Mahdi Soltanolkotabi

The more then hundred years old Bernstein inequality states that the supremum norm of the derivative of a trigonometric polynomial of fixed degree can be bounded from above by supremum norm of the polynomial itself. The reversed Bernstein…

Classical Analysis and ODEs · Mathematics 2023-03-09 Parvaneh Joharinad , Jürgen Jost , Sunhyuk Lim , Rostislav Matveev

The paper is devoted to two-weight estimates for the fractional maximal operators $\mathcal{M}^\alpha$ on general probability spaces equipped with a tree-like structure. For given $1<p\leq q<\infty$, we study the sharp universal upper bound…

Probability · Mathematics 2025-01-08 Rodrigo Bañuelos , Adam Osękowski

Using the log-convexity of the Gamma function and Euler's reflection formula, we give a new proof of a classical weighted sine product inequality. Two different parameter choices yield two competing upper bounds for the same product. We…

General Mathematics · Mathematics 2026-04-16 Augustine L. Mahu , Benoît F. Sehba , Cecilia D. Williams

In this note we prove optimal inequalities for bounded functions in terms of their deviation from their mean. These results extend and generalize some known inequalities due to Thong (2011) and Perfetti (2011)

Classical Analysis and ODEs · Mathematics 2014-03-03 Omran Kouba

A sharper uncertainty inequality which exhibits a lower bound larger than that in the classical N-dimensional Heisenberg's uncertainty principle is obtained, and extended from N-dimensional Fourier transform domain to two N-dimensional…

Mathematical Physics · Physics 2019-06-14 Zhichao Zhang

An isoperimetric inequality on the Hamming cube for exponents $\beta\ge 0.50057$ is proved, achieving equality on any subcube. This was previously known for $\beta\ge \log_2(3/2)\approx 0.585$. Improved bounds are also obtained at the…

Classical Analysis and ODEs · Mathematics 2024-07-18 Polona Durcik , Paata Ivanisvili , Joris Roos

We study martingale inequalities from an analytic point of view and show that a general martingale inequality can be reduced to a pair of deterministic inequalities in a small number of variables. More precisely, the optimal bound in the…

Probability · Mathematics 2014-10-21 Mathias Beiglböck , Marcel Nutz

In this paper we classify all positive extremal functions to a sharp weighted Sobolev inequality on the upper half space, which involves divergent operators with degeneracy on the boundary. As an application of the results, we can derive a…

Analysis of PDEs · Mathematics 2021-04-05 Jingbo Dou , Liming Sun , Lei Wang , Meijun Zhu

This note presents sharp inequalities for deviation probability of a general quadratic form of a random vector \(\xiv\) with finite exponential moments. The obtained deviation bounds are similar to the case of a Gaussian random vector. The…

Probability · Mathematics 2013-02-08 Vladimir Spokoiny

We prove sharp inequalities for determinants of Toeplitz operators and twisted Laplace operators on the two-sphere, generalizing the Moser-Trudinger-Onofri inequality. In particular a sharp version of conjectures of Gillet-Soule and Fang…

Complex Variables · Mathematics 2009-05-27 Robert J. Berman

We apply the shifted composition rule -- an information-theoretic principle introduced in our earlier work [AC23] -- to establish shift Harnack inequalities for the Langevin diffusion. We obtain sharp constants for these inequalities for…

Probability · Mathematics 2024-01-02 Jason M. Altschuler , Sinho Chewi

We prove a one-parameter family of sharp integral inequalities for functions on the $n$-dimensional unit ball. The inequalities are conformally invariant, and the sharp constants are attained for functions that are equivalent to a constant…

Functional Analysis · Mathematics 2012-01-31 Shibing Chen

We study the Hardy inequality when the singularity is placed on the boundary of a bounded domain in $\mathbb{R}^n$ that satisfies both an interior and exterior ball condition at the singularity. We obtain the sharp Hardy constant $n^2/4$ in…

Analysis of PDEs · Mathematics 2018-04-06 Gerassimos Barbatis , Stathis Filippas , Achilles Tertikas

The main purpose of this paper is to prove a sharp Sobolev inequality in an exterior of a convex bounded domain. There are two ingredients in the proof: One is the observation of some new isoperimetric inequalities with partial free…

Analysis of PDEs · Mathematics 2007-05-23 Meijun Zhu

This paper is concerned with Darcy's law for an incompressible viscous fluid flowing in a porous medium. We establish the sharp $O(\sqrt{\e})$ convergence rate in a periodically perforated and bounded domain in $R^d$ for $d\ge 2$, where…

Analysis of PDEs · Mathematics 2022-01-28 Zhongwei Shen