@Article{ATA-41-229, author = {Sun , Yingxin}, title = {A Rigidity Result for the Schiffer Conjecture on Domain with a Hole}, journal = {Analysis in Theory and Applications}, year = {2025}, volume = {41}, number = {3}, pages = {229--237}, abstract = {
Let $\Omega$ be a domain with a hole containing the origin in $\mathbb{R}^2$ and $u$ be a solution
to the problem
where $\partial^{\pm}\Omega$ represents the outer and inner boundaries of $\Omega,$ respectively, $c$ is a constant.
Let ${\mu}_k$ denote the $k{\rm th}$ Neumann eigenvalue of the Laplacian on $\Omega$ and${\Omega}_h$ is the hole.
We establish that if $\mu< {\mu}_8,$ then $\Omega$ is an annulus.