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In the influential paper \cite{Caflish-1980-CPAM} which was the starting point of the employment of Hilbert expansion method to the rigorous justifications of the fluid limits of the Boltzmann equation, Caflisch discovered an elegant and…

Analysis of PDEs · Mathematics 2025-08-26 Ning Jiang , Yi-Long Luo , Shaojun Tang

We present a spectral analysis for matrix scaling and operator scaling. We prove that if the input matrix or operator has a spectral gap, then a natural gradient flow has linear convergence. This implies that a simple gradient descent…

Data Structures and Algorithms · Computer Science 2019-04-09 Tsz Chiu Kwok , Lap Chi Lau , Akshay Ramachandran

In this note we provide an explicit lower bound on the spectral gap of one-dimensional Schr\"odinger operators with non-negative bounded potentials and subject to Neumann boundary conditions.

Spectral Theory · Mathematics 2022-10-13 Joachim Kerner

The non-cutoff Kac operator is a kinetic model for the non-cutoff radially symmetric Boltzmann operator. For Maxwellian molecules, the linearization of the non-cutoff Kac operator around a Maxwellian distribution is shown to be a function…

Analysis of PDEs · Mathematics 2012-04-05 Nicolas Lerner , Yoshinori Morimoto , Karel Pravda-Starov , Chao-Jiang Xu

This paper is to study the inelastic Boltzmann equation without Grad's angular cutoff assumption, where the well-posedness theory of the solution to the initial value problem is established for the Maxwellian molecules in a space of…

Mathematical Physics · Physics 2024-06-19 Kunlun Qi

The Boltzmann equation without an angular cutoff is considered when the initial data is a small perturbation of a global Maxwellian with an algebraic decay in the velocity variable. A well-posedness theory in the perturbative framework is…

Analysis of PDEs · Mathematics 2019-01-08 Ricardo Alonso , Yoshinori Morimoto , Weiran Sun , Tong Yang

We prove estimates for the variation of the eigenvalues of uniformly elliptic operators with homogeneous Dirichlet or Neumann boundary conditions upon variation of the open set on which an operator is defined. We consider operators of…

Spectral Theory · Mathematics 2012-04-16 Victor I. Burenkov , Pier Domenico Lamberti

The Cauchy problem for the Boltzmann equation with soft potential, in the framework of small perturbation of an equilibrium state, has been studied in many spaces. The method of strongly continuous semigroup has been applied by…

Analysis of PDEs · Mathematics 2024-02-08 Dingqun Deng

We consider restricted Boltzmann machines with a binary visible layer and a Gaussian hidden layer trained by an unlabelled dataset composed of noisy realizations of a single ground pattern. We develop a statistical mechanics framework to…

Disordered Systems and Neural Networks · Physics 2024-06-17 Alberto Fachechi , Elena Agliari , Miriam Aquaro , Anthony Coolen , Menno Mulder

We establish a lower bound on the spectral gap of the Laplace operator on special linear groups using conic optimisation. In particular, this provides a constructive (but computer assisted) proof that these groups have Kazhdan property (T).…

Group Theory · Mathematics 2017-10-11 Marek Kaluba , Piotr Nowak

We introduce a fast Fourier spectral method to compute linearized collision operators of the Boltzmann equation for variable hard-sphere gases. While the state-of-the-art method provides a computational cost O(MN^4 log N), with N being the…

Numerical Analysis · Mathematics 2025-09-16 Tianai Yin , Zhenning Cai , Yanli Wang

We study weak solutions of the homogeneous Boltzmann equation for Maxwellian molecules with a logarithmic singularity of the collision kernel for grazing collisions. Even though in this situation the Boltzmann operator enjoys only a very…

Analysis of PDEs · Mathematics 2017-07-24 Jean-Marie Barbaroux , Dirk Hundertmark , Tobias Ried , Semjon Vugalter

Let $M$ be a connected, noncompact, complete Riemannian manifold, consider the operator $L=\DD +\nn V$ for some $V\in C^2(M)$ with $\exp[V]$ integrable w.r.t. the Riemannian volume element. This paper studies the existence of the spectral…

Differential Geometry · Mathematics 2016-09-07 Feng-Yu Wang

Given a complex, separable Hilbert space $\cH$, we consider differential expressions of the type $\tau = - (d^2/dx^2) + V(x)$, with $x \in (a,\infty)$ or $x \in \bbR$. Here $V$ denotes a bounded operator-valued potential $V(\cdot) \in…

Spectral Theory · Mathematics 2013-03-19 Fritz Gesztesy , Rudi Weikard , Maxim Zinchenko

By using quasi--derivatives we develop a Fourier method for studying the spectral gaps of one dimensional Schr\"odinger operators with periodic singular potentials $v.$ Our results reveal a close relationship between smoothness of…

Spectral Theory · Mathematics 2009-03-31 Plamen Djakov , Boris Mityagin

We prove global existence of smooth solutions near Maxwellians for the non-cutoff Vlasov-Poisson-Boltzmann system in the weakly collisional regime. To address the weak dissipation of the non-cutoff linearized Boltzmann operator, we develop…

Analysis of PDEs · Mathematics 2025-10-07 Yuanjie Lei , Shuangqian Liu , Qinghua Xiao , Huijiang Zhao

We examine two kinds of spectral theoretic situations: First, we recall the case of self-adjoint half-line Schr\"odinger operators on $[a,\infty)$, $a\in\mathbb{R}$, with a regular finite end point $a$ and the case of Schr\"odinger…

Spectral Theory · Mathematics 2020-02-25 Fritz Gesztesy , Maxim Zinchenko

For the Maxwellian molecules or hard potentials case, we verify the smoothing effect for the spatially inhomogeneous Boltzmann equation without angular cutoff. Given initial data with low regularity, we prove its solutions at any positive…

Analysis of PDEs · Mathematics 2024-01-22 Jun-Ling Chen , Wei-Xi Li , Chao-Jiang Xu

Let $L$ be a non-negative self-adjoint operator on $L^2(\mathbb{R}^n)$. By spectral theory, we can define the operator $F(L)$, which is bounded on $L^2(X)$, for any bounded Borel function $F$. In this paper, we study the sharp weighted…

Classical Analysis and ODEs · Mathematics 2012-03-19 The Anh Bui

In this paper we obtain sharp Lieb-Thirring inequalities for a Schr\"odinger operator on semi-axis with a matrix potential and show how they can be used to other related problems. Among them are spectral inequalities on star graphs and…

Mathematical Physics · Physics 2019-12-10 Pavel Exner , Ari Laptev , Muhammad Usman