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We determine a counterexample to strong diamagnetism for the Laplace operator in the unit disc with a uniform magnetic field and Robin boundary condition. The example follows from the accurate asymptotics of the lowest eigenvalue when the…

Spectral Theory · Mathematics 2020-08-26 Ayman Kachmar , Mikael P. Sundqvist

For $\alpha\in(0,\pi)$, let $U_\alpha$ denote the infinite planar sector of opening $2\alpha$, \[ U_\alpha=\big\{ (x_1,x_2)\in\mathbb R^2: \big|\arg(x_1+ix_2) \big|<\alpha \big\}, \] and $T^\gamma_\alpha$ be the Laplacian in…

Spectral Theory · Mathematics 2018-04-18 Magda Khalile , Konstantin Pankrashkin

The spectral theory of the p-Laplacian is well developed for classical Dirichlet and Neumann boundary conditions, but the transitional Robin regime on exterior domains remains largely unexplored. This paper studies a weighted p-Laplacian…

Analysis of PDEs · Mathematics 2025-12-29 Subha Pal , Sarath Sasi

Motivated by pioneering works of Bandle and Wagner, given a bounded Lipschitz domain $\Omega \subset \mathbb R^d$ with $d\ge3$, we consider the Robin-Laplacian torsional rigidity $\tau_\alpha(\Omega)$ with negative boundary parameter…

Optimization and Control · Mathematics 2026-01-15 Nunzia Gavitone , David Krejcirik , Gloria Paoli

We study some properties of Laplacian eigenvalues with negative Robin boundary conditions. We will show some monotonicity properties on annuli of the first eigenvalue by means of shape optimization techniques.

Analysis of PDEs · Mathematics 2017-09-15 Leonardo Trani

In this paper, we deal with functionals involving the torsion and the first eigenvalue of the Laplacian with Robin boundary conditions (to which we refer as Robin Torsion and Robin Eigenvalue), with other geometrical quantities, in the…

Analysis of PDEs · Mathematics 2026-03-30 Rosa Barbato , Alba Lia Masiello , Rossano Sannipoli

It has recently been conjectured by Bogosel, Henrot, and Michetti that the second positive eigenvalue of the Neumann Laplacian is maximized, among all planar convex domains of fixed perimeter, by the rectangle with one edge length equal to…

Spectral Theory · Mathematics 2025-02-18 Vladimir Lotoreichik , Jonathan Rohleder

The classical Szego-Weinberger inequality states that among bounded planar domains of given area, the first nonzero Neumann eigenvalue is maximized by a disk. Recently, it was shown by Girouard, Nadirashvili and Polterovich that, for simply…

Spectral Theory · Mathematics 2010-07-28 Guillaume Poliquin , Guillaume Roy-Fortin

We study the family of operators $\{\mathcal{R}_a\}_{a\in [0,+\infty)}$ associated to the Robin-type problems in a bounded domain $\Omega\subset\mathbb{R}^2$ $$ \begin{cases} -\Delta u = f & \text{in } \Omega, \\ 2 \bar \nu \partial_{\bar…

Analysis of PDEs · Mathematics 2026-02-18 Joaquim Duran

Let $\Omega\subset \mathbb{R}^2$ be the exterior of a convex polygon whose side lengths are $\ell_1,...,\ell_M$. For $\alpha>0$, let $H^\Omega_\alpha$ denote the Laplacian in $\Omega$, $u\mapsto -\Delta u$, with the Robin boundary…

Spectral Theory · Mathematics 2015-02-20 Konstantin Pankrashkin

For every given $\beta<0$, we study the problem of maximizing the first Robin eigenvalue of the Laplacian $\lambda_\beta(\Omega)$ among convex (not necessarily smooth) sets $\Omega\subset\mathbb{S}^{n}$ with fixed perimeter. In particular,…

Analysis of PDEs · Mathematics 2025-07-30 Paolo Acampora , Antonio Celentano , Emanuele Cristoforoni , Carlo Nitsch , Cristina Trombetti

We study the spectrum of the Laplacian on the hemisphere with Robin boundary conditions. It is found that the eigenvalues fall into small clusters around the Neumann spectrum, and satisfy a Szeg\H{o} type limit theorem. Sharp upper and…

Spectral Theory · Mathematics 2020-09-01 Zeév Rudnick , Igor Wigman

This paper aims to show that, in the limit of strong magnetic fields, the optimal domains for eigenvalues of magnetic Laplacians tend to exhibit symmetry. We establish several asymptotic bounds on magnetic eigenvalues to support this…

Spectral Theory · Mathematics 2025-09-11 Vladimir Lotoreichik , Léo Morin

We investigate how the lowest eigenvalue of a magnetic Laplacian depends on the geometry of a planar domain with a disk shaped hole, where the magnetic field is generated by a singular flux. Under Dirichlet boundary conditions on the inner…

Analysis of PDEs · Mathematics 2025-05-14 Mrityunjoy Ghosh , Ayman Kachmar

The sum of the first n energy levels of the planar Laplacian with constant magnetic field of given total flux is shown to be maximal among triangles for the equilateral triangle, under normalization of the ratio (moment of inertia)/(area)^3…

Analysis of PDEs · Mathematics 2015-05-27 Richard S. Laugesen , Jian Liang , Arindam Roy

We discuss several properties of eigenvalues and eigenfunctions of the $p$-Laplacian on a ball subject to zero Dirichlet boundary conditions. Among main results, in two dimensions, we show the existence of nonradial eigenfunctions which…

Analysis of PDEs · Mathematics 2017-06-12 Vladimir Bobkov , Pavel Drabek

In this paper, we study the first eigenvalue of the Laplacian on doubly connected domains when Robin and Dirichlet conditions are imposed on the outer and the inner part of the boundary, respectively. We provide that the spherical shell…

Analysis of PDEs · Mathematics 2024-10-10 Nunzia Gavitone , Gianpaolo Piscitelli

We consider the torsional rigidity and the principal eigenvalue related to the Laplace operator with Dirichlet and Robin boundary conditions. The goal is to find upper and lower bounds to products of suitable powers of the quantities above…

Analysis of PDEs · Mathematics 2025-12-18 Giuseppe Buttazzo , Simone Cito , Francesco Solombrino

In this note we consider achieving the largest principle eigenvalue of a Robin Laplacian on a bounded domain $\Omega$ by optimizing the Robin parameter function under an integral constraint. The main novelty of our approach lies in…

Spectral Theory · Mathematics 2024-08-22 Pavel Exner , Hynek Kovarik

Let $\Omega$ be a bounded, smooth domain of $\mathbb R^N$, $N\ge 2$. In this paper, we prove some inequalities involving the first Robin eigenvalue of the $p$-laplacian operator. In particular, we prove an upper bound for the first Robin…

Analysis of PDEs · Mathematics 2025-04-02 Rosa Barbato , Francesco Della Pietra