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We prove the validity of regularizing properties of a double layer potential associated to the fundamental solution of a {\em nonhomogeneous} second order elliptic differential operator with constant coefficients in Schauder spaces by…

Analysis of PDEs · Mathematics 2021-03-15 Francesco Dondi , Massimo Lanza de Cristoforis

We consider the Schr\"odinger operator in the plane with delta-potential supported by a curve. For the cases of an infinite curve and a finite loop we give estimates on the lower bound of the spectrum expressed explicitly through the…

Spectral Theory · Mathematics 2010-11-11 Igor Lobanov , Vladimir Lotoreichik , Igor Popov

Using techniques from harmonic analysis, we derive several sharp stability estimates for the second order Heisenberg Uncertainty Principle. We also present the explicit lower and upper bounds for the sharp stability constants and compute…

Analysis of PDEs · Mathematics 2025-12-23 Anh Xuan Do , Nguyen Lam , Guozhen Lu

We prove a lower bound for the modulus of the amplitude for a two-body process at large scattering angle. This is based on the interplay of the analyticity of the amplitude and the positivity properties of its absorptive part. The…

High Energy Physics - Theory · Physics 2019-07-03 Henri Epstein , André Martin

This paper communicates recent results in theory of complex symmetric operators and shows, through two non-trivial examples, their potential usefulness in the study of Schr\"odinger operators. In particular, we propose a formula for…

Mathematical Physics · Physics 2008-06-10 Emil Prodan , Stephan R. Garcia , Mihai Putinar

We compare the usual operator modulus with two symmetrized variants, the arithmetic symmetric modulus and the quadratic symmetric modulus. For every unitarily invariant norm, we determine sharp equivalence constants among these three…

Functional Analysis · Mathematics 2026-03-03 Teng Zhang

We give a new lower bound for the first gap $\lambda_2 - \lambda_1$ of the Dirichlet eigenvalues of the Schr{\"o}dinger operator on a bounded convex domain $\Omega$ in R$^n$ or S$^n$ and greatly sharpens the previous estimates. The new…

Differential Geometry · Mathematics 2007-05-23 Jun Ling

Quasi branch and bound is a recently introduced generalization of branch and bound, where lower bounds are replaced by a relaxed notion of quasi-lower bounds, required to be lower bounds only for sub-cubes containing a minimizer. This paper…

Optimization and Control · Mathematics 2020-05-29 Nadav Dym

In this paper, we give two explicit examples of unbounded linear maximal monotone operators. The first unbounded linear maximal monotone operator $S$ on $\ell^{2}$ is skew. We show its domain is a proper subset of the domain of its adjoint…

Functional Analysis · Mathematics 2009-09-16 Heinz H. Bauschke , Xianfu Wang , Liangjin Yao

We consider symmetric hypothesis testing in quantum statistics, where the hypotheses are density operators on a finite-dimensional complex Hilbert space, representing states of a finite quantum system. We prove a lower bound on the…

Quantum Physics · Physics 2009-04-30 Michael Nussbaum , Arleta Szkoła

Motivated by the study of $Q$-learning algorithms in reinforcement learning, we study a class of stochastic approximation procedures based on operators that satisfy monotonicity and quasi-contractivity conditions with respect to an…

Machine Learning · Computer Science 2019-06-25 Martin J. Wainwright

In this paper we analyze iterations of the obstacle problem for two different operators. We solve iteratively the obstacle problem from above or below for two different differential operators with obstacles given by the previous functions…

Analysis of PDEs · Mathematics 2024-02-05 Irene Gonzalvez , Alfredo Miranda , Julio D. Rossi

We study arbitrary order symmetry operators for the linear Schr\"odinger equations with arbitrary number of spatial variables. We deduce determining equations for coefficient functions of such operators and consider in detail some cases…

Mathematical Physics · Physics 2016-03-08 A. G. Nikitin

We study upper bounds on the Schur multiplier norm of Loewner matrices for concave and convex functions. These bounds then immediately lead to upper bounds on the ratio of Schatten $q$-norms of commutators…

Functional Analysis · Mathematics 2014-10-24 Koenraad M. R. Audenaert

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

Error estimation of difference operators on irregular nodes is discussed. We can obtain the similar estimates of the errors. However, the error estimate for the difference operators for the second derivatives becomes lower because of…

Numerical Analysis · Mathematics 2017-07-04 Hiroshi Isshiki , Takafumi Kawamura , Daisuke Kitazawa

We establish H\"ormander-type $L^2$-estimates for the $\overline{\partial}$-operators that hold uniformly for all nontrivial flat holomorphic line bundles on compact K\"ahler manifolds. Our result can be regarded as a…

Complex Variables · Mathematics 2023-04-04 Yoshinori Hashimoto , Takayuki Koike

We address the problem, not of the determination -- which usually needs numerical methods -- but of an accurate analytical estimation of the distance of a raw elasticity tensor to cubic symmetry and to orthotropy. We point out that there…

Classical Physics · Physics 2022-06-08 Rodrigue Desmorat , Boris Kolev

We study a model Schr\"odinger operator with constant magnetic field on an infinite wedge with Neumann boundary condition. The magnetic field is assumed to be tangent to a face. We compare the bottom of the spectrum to the model spectral…

Analysis of PDEs · Mathematics 2014-02-20 Nicolas Popoff

Recently, a remarkable correspondence has been unveiled between a certain class of ordinary linear differential equations (ODE) and integrable models. In the first part of the report, we survey the results concerning the 2nd order…

Exactly Solvable and Integrable Systems · Physics 2007-05-23 J. Suzuki