Planar Hamiltonian systems: Index theory and applications to the existence of subharmonics. (January 2023)

• Record Type: Journal Article
• Authors: Boscaggin, Alberto; Muñoz-Hernández, Eduardo
• Is Part Of: Nonlinear analysis. Volume 226(2023)
• Publication Date: 2023-01
• Subjects: 34C25 -- 37B30 -- 37J12; Planar Hamiltonian systems -- Subharmonic solutions -- Conley–Zehnder index -- Rotation number -- Poincaré–Birkhoff theorem; Mathematical analysis -- Periodicals; Functional analysis -- Periodicals; Nonlinear theories -- Periodicals; Analyse mathématique -- Périodiques; Analyse fonctionnelle -- Périodiques; Théories non linéaires -- Périodiques; Functional analysis; Mathematical analysis; Nonlinear theories; Periodicals; Electronic journals; 515.7248
• DOI: 10.1016/j.na.2022.113142
• Languages: English
• ISSNs: 0362-546X

Abstract

Abstract: We consider a planar Hamiltonian system of the type J z ′ = ∇ z H ( t, z ), where H : R × R 2 → R is a function periodic in the time variable, such that ∇ z H ( t, 0 ) ≡ 0 and ∇ z H ( t, z ) is asymptotically linear for | z | → + ∞ . After revisiting the index theory for linear planar Hamiltonian systems, by using the Poincaré–Birkhoff fixed point theorem we prove that the above nonlinear system has subharmonic solutions of any order k large enough, whenever the rotation numbers (or, equivalently, the mean Conley–Zehnder indices) of the linearizations of the system at zero and at infinity are different. Applications are given to the case of planar Hamiltonian systems coming from second order scalar ODEs.