Kolmogorov's Theorem for Degenerate Hamiltonian Systems with Continuous Parameters

Fuente: arXiv
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Main Authors: Du, Jiayin, Li, Yong, Zhang, Hongkun
Format: Preprint
Published: 2022
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_version_ 1866910582903406592
author Du, Jiayin
Li, Yong
Zhang, Hongkun
author_facet Du, Jiayin
Li, Yong
Zhang, Hongkun
contents In this paper, we investigate Kolmogorov type theorems for small perturbations of degenerate Hamiltonian systems. These systems are index by a parameter $ξ$ as \( H(y,x,ξ) = \langleω(ξ),y\rangle + \varepsilon P(y,x,ξ,\varepsilon) \) where $\varepsilon>0$. We assume that the frequency map, $ω$, is continuous with respect to $ξ$. Additionally, the perturbation function, $P(y,x,\cdot, \varepsilon)$, maintains Hölder continuity about $ξ$. We prove that persistent invariant tori retain the same frequency as those of the unperturbed tori, under certain topological degree conditions and a weak convexity condition for the frequency mapping. Notably, this paper presents, to our understanding, pioneering results on the KAM theorem under such conditions-with only assumption of continuous dependence of frequency mapping $ω$ on the parameter.
format Preprint
id arxiv_https___arxiv_org_abs_2206_05461
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Kolmogorov's Theorem for Degenerate Hamiltonian Systems with Continuous Parameters
Du, Jiayin
Li, Yong
Zhang, Hongkun
Dynamical Systems
In this paper, we investigate Kolmogorov type theorems for small perturbations of degenerate Hamiltonian systems. These systems are index by a parameter $ξ$ as \( H(y,x,ξ) = \langleω(ξ),y\rangle + \varepsilon P(y,x,ξ,\varepsilon) \) where $\varepsilon>0$. We assume that the frequency map, $ω$, is continuous with respect to $ξ$. Additionally, the perturbation function, $P(y,x,\cdot, \varepsilon)$, maintains Hölder continuity about $ξ$. We prove that persistent invariant tori retain the same frequency as those of the unperturbed tori, under certain topological degree conditions and a weak convexity condition for the frequency mapping. Notably, this paper presents, to our understanding, pioneering results on the KAM theorem under such conditions-with only assumption of continuous dependence of frequency mapping $ω$ on the parameter.
title Kolmogorov's Theorem for Degenerate Hamiltonian Systems with Continuous Parameters
topic Dynamical Systems
url https://arxiv.org/abs/2206.05461