3 papers
math.DS2026
An affine Birkhoff-Kellogg type result in product spaces and its application to differential systems
Alessandro Calamai, Gennaro Infante, Giuseppe Antonio Veltri
We prove a version of the Birkhoff-Kellogg theorem in product spaces, under affine transformations. This is a fairly natural framework that arises when dealing with parameter-depen…
math.CA2026
An eigenvalue result for Neumann BVPs with functional terms
Giuseppe Antonio Veltri
We study the existence and localization of eigenvalue-eigenfunction pairs for parameter-dependent Neumann BVPs with a functional term. By reformulating the problems as a Hammerstei…
math.CA2025
An eigenvalue result for Hammerstein integral equations with sign changing nonlinearities and functional terms
Gennaro Infante, Giuseppe Antonio Veltri
We discuss, via a version of the Birkhoff-Kellogg theorem, the existence of positive and negative eigenvalues of Hammerstein integral equations with sign-changing nonlinearities an…