The Poincaré–Birkhoff Theorem for a Class of Degenerate Planar Hamiltonian Systems

Autor: López-Gómez Julián, Muñoz-Hernández Eduardo, Zanolin Fabio
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Advanced Nonlinear Studies, Vol 21, Iss 3, Pp 489-499 (2021)
Druh dokumentu: article
ISSN: 1536-1365
2169-0375
DOI: 10.1515/ans-2021-2137
Popis: In this paper, we investigate the problem of the existence and multiplicity of periodic solutions to the planar Hamiltonian system x′=-λ⁢α⁢(t)⁢f⁢(y)x^{\prime}=-\lambda\alpha(t)f(y), y′=λ⁢β⁢(t)⁢g⁢(x)y^{\prime}=\lambda\beta(t)g(x), where α,β\alpha,\beta are non-negative 𝑇-periodic coefficients and λ>0\lambda>0. We focus our study to the so-called “degenerate” situation, namely when the set Z:=supp⁡α∩supp⁡βZ:=\operatorname{supp}\alpha\cap\operatorname{supp}\beta has Lebesgue measure zero. It is known that, in this case, for some choices of 𝛼 and 𝛽, no nontrivial 𝑇-periodic solution exists. On the opposite, we show that, depending of some geometric configurations of 𝛼 and 𝛽, the existence of a large number of 𝑇-periodic solutions (as well as subharmonic solutions) is guaranteed (for λ>0\lambda>0 and large). Our proof is based on the Poincaré–Birkhoff twist theorem. Applications are given to Volterra’s predator-prey model with seasonal effects.
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