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Register a new userAn eigenvalue estimate for a Robin $p$-Laplacian in $C^1$ domains
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Authors
Konstantin Pankrashkin
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Let $Omegasubset mathbb{R}^n$ be a bounded $C^1$ domain and $p>1$. For $alpha>0$, define the quantity [ Lambda(alpha)=inf_{uin W^{1,p}(Omega),, u otequiv 0} Big(int_Omega | abla u|^p,mathrm{d}x - alpha int_{partialOmega} |u|^p ,mathrm{d} sBig)Big/ int_Omega |u|^p,mathrm{d} x ] with $mathrm{d} s$ being the hypersurface measure, which is the lowest eigenvalue of the $p$-laplacian in $Omega$ with a non-linear $alpha$-dependent Robin boundary condition. We show the asymptotics $Lambda(alpha) =(1-p)alpha^{p/(p-1)}+o(alpha^{p/(p-1)})$ as $alpha$ tends to $+infty$. The result was only known for the linear case $p=2$ or under stronger smoothness assumptions. Our proof is much shorter and is based on completely different and elementary arguments, and it allows for an improved remainder estimate for $C^{1,lambda}$ domains.
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We consider a nonlinear elliptic equation driven by the Robin $p$-Laplacian plus an indefinite potential. In the reaction we have the competing effects of a strictly $(p-1)$-sublinear parametric term and of a $(p-1)$-linear and nonuniformly nonresonant term. We study the set of positive solutions as the parameter $lambda>0$ varies. We prove a bifurcation-type result for large values of the positive parameter $lambda$. Also, we show that for all admissible $lambda>0$, the problem has a smallest positive solution $overline{u}_lambda$ and we study the monotonicity and continuity properties of the map $lambdamapstooverline{u}_lambda$.
In this paper we study the best constant in a Hardy inequality for the p-Laplace operator on convex domains with Robin boundary conditions. We show, in particular, that the best constant equals $((p-1)/p)^p$ whenever Dirichlet boundary conditions are imposed on a subset of the boundary of non-zero measure. We also discuss some generalizations to non-convex domains.
We study the discrete spectrum of the Robin Laplacian $Q^{Omega}_alpha$ in $L^2(Omega)$, [ umapsto -Delta u, quad dfrac{partial u}{partial n}=alpha u text{ on }partialOmega, ] where $Omegasubset mathbb{R}^{3}$ is a conical domain with a regular cross-section $Thetasubset mathbb{S}^2$, $n$ is the outer unit normal, and $alpha>0$ is a fixed constant. It is known from previous papers that the bottom of the essential spectrum of $Q^{Omega}_alpha$ is $-alpha^2$ and that the finiteness of the discrete spectrum depends on the geometry of the cross-section. We show that the accumulation of the discrete spectrum of $Q^Omega_alpha$ is determined by the discrete spectrum of an effective Hamiltonian defined on the boundary and far from the origin. By studying this model operator, we prove that the number of eigenvalues of $Q^{Omega}_alpha$ in $(-infty,-alpha^2-lambda)$, with $lambda>0$, behaves for $lambdato0$ as [ dfrac{alpha^2}{8pi lambda} int_{partialTheta} kappa_+(s)^2d s +oleft(frac{1}{lambda}right), ] where $kappa_+$ is the positive part of the geodesic curvature of the cross-section boundary.
We consider quasimodes on planar domains with a partially rectangular boundary. We prove that for any $epsilon_0>0$, an $O(lambda^{-epsilon_0})$ quasimode must have $L^2$ mass in the wings bounded below by $lambda^{-2-delta}$ for any $delta>0$. The proof uses the authors recent work on 0-Gevrey smooth domains to approximate quasimodes on $C^{1,1}$ domains. There is an improvement for $C^{2,alpha}$ domains.
We investigate multiplicity and symmetry properties of higher eigenvalues and eigenfunctions of the $p$-Laplacian under homogeneous Dirichlet boundary conditions on certain symmetric domains $Omega subset mathbb{R}^N$. By means of topological arguments, we show how symmetries of $Omega$ help to construct subsets of $W_0^{1,p}(Omega)$ with suitably high Krasnoselskiu{i} genus. In particular, if $Omega$ is a ball $B subset mathbb{R}^N$, we obtain the following chain of inequalities: $$ lambda_2(p;B) leq dots leq lambda_{N+1}(p;B) leq lambda_ominus(p;B). $$ Here $lambda_i(p;B)$ are variational eigenvalues of the $p$-Laplacian on $B$, and $lambda_ominus(p;B)$ is the eigenvalue which has an associated eigenfunction whose nodal set is an equatorial section of $B$. If $lambda_2(p;B)=lambda_ominus(p;B)$, as it holds true for $p=2$, the result implies that the multiplicity of the second eigenvalue is at least $N$. In the case $N=2$, we can deduce that any third eigenfunction of the $p$-Laplacian on a disc is nonradial. The case of other symmetric domains and the limit cases $p=1$, $p=infty$ are also considered.
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