Non-Ljusternik--Schnirelman eigenvalues of the pure $p$-Laplacian exist

Fuente: arXiv
Saved in:
Bibliographic Details
Main Author: Bobkov, Vladimir
Format: Preprint
Published: 2026
Subjects:
Online Access:
Tags: Add Tag
No Tags, Be the first to tag this record!
_version_ 1866914437555814400
author Bobkov, Vladimir
author_facet Bobkov, Vladimir
contents An old and well-known open problem in the critical point theory asks whether, for some $p \neq 2$ and some bounded domain $Ω$, there exists a critical value of the $p$-Dirichlet energy $\|\nabla u\|_p^p$ over an $L^p(Ω)$-sphere in $W_0^{1,p}(Ω)$ lying outside of a Ljusternik--Schnirelman type sequence of critical values, the latter will be called LS eigenvalues of the $p$-Laplacian. In this work, we provide a positive answer by showing the existence of a non-LS eigenvalue when $p>2$ is sufficiently close to $2$ and $Ω$ is just a planar rectangle close to the square. The arguments pursue the observation that a simple eigenvalue of the Laplacian can be a meeting point for several branches of eigenvalues of the $p$-Laplacian as $p$ varies. Since LS eigenvalues are continuous with respect to $p$ and exhaust the whole spectrum when $p=2$, we deduce that at least one of the branches must contain non-LS eigenvalues.
format Preprint
id arxiv_https___arxiv_org_abs_2604_01138
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Non-Ljusternik--Schnirelman eigenvalues of the pure $p$-Laplacian exist
Bobkov, Vladimir
Analysis of PDEs
Functional Analysis
Spectral Theory
35J92, 35P30, 47J10
An old and well-known open problem in the critical point theory asks whether, for some $p \neq 2$ and some bounded domain $Ω$, there exists a critical value of the $p$-Dirichlet energy $\|\nabla u\|_p^p$ over an $L^p(Ω)$-sphere in $W_0^{1,p}(Ω)$ lying outside of a Ljusternik--Schnirelman type sequence of critical values, the latter will be called LS eigenvalues of the $p$-Laplacian. In this work, we provide a positive answer by showing the existence of a non-LS eigenvalue when $p>2$ is sufficiently close to $2$ and $Ω$ is just a planar rectangle close to the square. The arguments pursue the observation that a simple eigenvalue of the Laplacian can be a meeting point for several branches of eigenvalues of the $p$-Laplacian as $p$ varies. Since LS eigenvalues are continuous with respect to $p$ and exhaust the whole spectrum when $p=2$, we deduce that at least one of the branches must contain non-LS eigenvalues.
title Non-Ljusternik--Schnirelman eigenvalues of the pure $p$-Laplacian exist
topic Analysis of PDEs
Functional Analysis
Spectral Theory
35J92, 35P30, 47J10
url https://arxiv.org/abs/2604.01138