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In this work, we study the extremal functions of the log-Sobolev functional on compact metric measure spaces satisfying the $\mathrm{RCD}^*(K,N)$ condition for $K$ in $\mathbb{R}$ and $N$ in $(2,\infty)$. We show the existence, regularity…

Analysis of PDEs · Mathematics 2023-02-07 Samuel Drapeau , Liming Yin

We discuss approximation of extremal functions by polynomials in the weighted Bergman spaces $A^p_\alpha$ where $-1 < \alpha < 0$ and $-1 < \alpha < p-2$. We obtain bounds on how close the approximation is to the true extremal function in…

Complex Variables · Mathematics 2017-05-19 Timothy Ferguson

We determine the optimal majorant $M^+$ and minorant $M^-$ of exponential type for the truncation of $x\mapsto (x^2+a^2)^{-1}$ with respect to general de Branges measures. We prove that \[ \int_\mathbb{R} (M^+ - M^-) |E(x)|^{-2}dx =…

Classical Analysis and ODEs · Mathematics 2016-08-22 Friedrich Littmann , Mark Spanier

We characterize the function $\varphi$ of minimal $L^1$ norm among all functions $f$ of exponential type at most $\pi$ for which $f(0)=1$. This function, studied by H\"{o}rmander and Bernhardsson in 1993, has only real zeros $\pm \tau_n$,…

Classical Analysis and ODEs · Mathematics 2026-01-26 Andriy Bondarenko , Joaquim Ortega-Cerdà , Danylo Radchenko , Kristian Seip

We establish a supercritical Trudinger-Moser type inequality for the $k$-Hessian operator on the space of the $k$-admissible radially symmetric functions $\Phi^{k}_{0,\mathrm{rad}}(B)$, where $B$ is the unit ball in $\mathbb{R}^{N}$. We…

Analysis of PDEs · Mathematics 2024-07-16 José Francisco de Oliveira , João Marcos do Ó , Pedro Ubilla

We derive the exact asymptotics of \[ P\left( \sup_{t\ge 0} \Bigl( X_1(t) - \mu_1 t\Bigr)> u, \ \sup_{s\ge 0} \Bigl( X_2(s) - \mu_2 s\Bigr)> u \right), \ \ u\to\infty, \] where $(X_1(t),X_2(s))_{t,s\ge0}$ is a correlated two-dimensional…

Probability · Mathematics 2020-03-09 Krzysztof Debicki , Lanpeng Ji , Tomasz Rolski

Extremal length is an important conformal invariant on Riemann surface. It is closely related to the geometry of Teichmuller metric on Teichmuller space. By identifying extremal length functions with energy of harmonic maps from Riemann…

Geometric Topology · Mathematics 2016-08-30 Lixin Liu , Weixu Su

We study extremal properties of the determinant of the Laplacian in the Bergman metric on the moduli space of compact genus two Riemann surfaces. By a combination of analytical and numerical methods we identify four non-degenerate critical…

Spectral Theory · Mathematics 2007-05-23 C. Klein , A. Kokotov , D. Korotkin

We show that a real-valued function $f$ in the shift-invariant space generated by a totally positive function of Gaussian type is uniquely determined, up to a sign, by its absolute values $\{|f(\lambda)|: \lambda \in \Lambda \}$ on any set…

Classical Analysis and ODEs · Mathematics 2020-12-16 José Luis Romero

We show that any function in a Bergman space with exponential type weights admits a representation in terms of an infinite series of kernel functions.

Complex Variables · Mathematics 2015-09-01 Hicham Arroussi , Jordi Pau

On spaces of finite signed Borel measures on a metric space one has introduced the Fortet-Mourier and Dudley norms, by embedding the measures into the dual space of the Banach space of bounded Lipschitz functions, equipped with different --…

Functional Analysis · Mathematics 2023-05-16 Sander C. Hille , Esmee S. Theewis

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

In this paper, we prove the existence of extremal functions for the best constant of embedding from anisotropic space, allowing some of the Sobolev exponents to be equal to $1$. We prove also that the extremal functions satisfy a partial…

Analysis of PDEs · Mathematics 2018-04-18 Françoise Demengel , Thomas Dumas

Let $\mu$ be a Borel probability measure with compact support. We consider exponential type orthonormal bases, Riesz bases and frames in $L^2(\mu)$. We show that if $L^2(\mu)$ admits an exponential frame, then $\mu$ must be of pure type. We…

Functional Analysis · Mathematics 2013-03-04 Xing-Gang He , Chun-Kit Lai , Ka-Sing Lau

Extremal spectral properties of Lawson tau-surfaces are investigated. The Lawson tau-surfaces form a two-parametric family of tori or Klein bottles minimally immersed in the standard unitary three-dimensional sphere. A Lawson tau-surface…

Spectral Theory · Mathematics 2012-01-24 Alexei V. Penskoi

We solve the problem of finding optimal entire approximations of prescribed exponential type (unrestricted, majorant and minorant) for a class of truncated and odd functions with a shifted exponential subordination, minimizing the…

Classical Analysis and ODEs · Mathematics 2021-09-30 Emanuel Carneiro , Friedrich Littmann

We consider the discrete Gaussian Free Field in a square box in $\mathbb Z^2$ of side length $N$ with zero boundary conditions and study the joint law of its properly-centered extreme values ($h$) and their scaled spatial positions ($x$) in…

Probability · Mathematics 2016-06-24 Marek Biskup , Oren Louidor

We consider partition functions Z(g) = exp (-g(x))dx where g is a nonnegative polynomial action (a degree-2n form) vanishing only at the origin. Such integrals, known as integral discriminants, appear in statistical mechanics, quantum field…

Functional Analysis · Mathematics 2026-02-19 Jean B Lasserre

Let $\{X_i(t),t\ge0\}, 1\le i\le n$ be mutually independent centered Gaussian processes with almost surely continuous sample paths. We derive the exact asymptotics of $$ P\left(\exists_{t \in [0,T]} \forall_{i=1 ... n} X_i(t)> u \right) $$…

Probability · Mathematics 2015-05-26 Krzysztof Dȩbicki , Enkelejd Hashorva , Lanpeng Ji , Kamil Tabiś

Imagine that measurements are made at times $t_0$ and $t_1$ of the trajectory of a physical system whose governing laws are given approximately by a class ${\cal A}$ of so-called {\em prior vector fields}. Because the physical laws are not…

Differential Geometry · Mathematics 2011-04-15 Lyle Noakes