Eigenvalues of a third order BVP subject to functional BCs
Gennaro Infante, Paolo Lucisano
TL;DR
This work addresses eigenvalues of a third-order boundary value problem with nonlocal functional boundary conditions and nonlinearities depending on higher derivatives. It reframes the problem as a perturbed Hammerstein integral equation in $C^2[0,1]$ with a compact operator $T = F + \Gamma$, where $F u(t) = \int_{0}^{1} k(t,s) f(s,u,u',u'') ds$ and $\Gamma u(t) = \gamma_1(t) H_1[u] + \gamma_2(t) H_2[u]$. Using a variant of the Birkhoff-Kellogg invariant-direction theorem, the authors establish the existence of eigenvalues of opposite signs with corresponding eigenfunctions localized by the $C^2$-norm, and they provide conditions under which uncountably many eigenpairs arise as the radius $\rho$ varies. An explicit example demonstrates the applicability and computability of the constants involved, highlighting the results’ relevance for nonlocal third-order problems and related applications.
Abstract
We discuss the existence of eigenvalues for a third order boundary value problem subject to functional boundary conditions and higher order derivative dependence in the nonlinearities. We prove the existence of positive and negative eigenvalues and provide a localization of the corresponding eigenfunctions in terms of their norm. The methodology involves a version of the classical Birkhoff-Kellogg theorem. We illustrate the applicability of the theoretical results in an example.
