Normalization flow and Poincaré-Dulac theory

Fuente: arXiv
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Main Author: Chernyshev, Andrey
Format: Preprint
Published: 2026
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author Chernyshev, Andrey
author_facet Chernyshev, Andrey
contents In this article, we develop a new approach to the Poincaré--Dulac normal form theory for a system of differential equations near a singular point. Using the continuous averaging method, we construct a normalization flow that moves a vector field to its normal form. We prove that, in the algebra of formal vector fields (given by power series), the normalization procedure achieves full normalization. When convergence is taken into account, we show that the radius of convergence admits a lower bound of order $1/(1+Aδ)$, with $A>0$, as $δ\to +\infty$. Based on the methods of this work and on the approaches of \cite{Tres2}, we provide a new proof of the Siegel--Brjuno theorem on the convergence of the normalizing transformation.
format Preprint
id arxiv_https___arxiv_org_abs_2601_03147
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Normalization flow and Poincaré-Dulac theory
Chernyshev, Andrey
Dynamical Systems
34C29, 37G05
In this article, we develop a new approach to the Poincaré--Dulac normal form theory for a system of differential equations near a singular point. Using the continuous averaging method, we construct a normalization flow that moves a vector field to its normal form. We prove that, in the algebra of formal vector fields (given by power series), the normalization procedure achieves full normalization. When convergence is taken into account, we show that the radius of convergence admits a lower bound of order $1/(1+Aδ)$, with $A>0$, as $δ\to +\infty$. Based on the methods of this work and on the approaches of \cite{Tres2}, we provide a new proof of the Siegel--Brjuno theorem on the convergence of the normalizing transformation.
title Normalization flow and Poincaré-Dulac theory
topic Dynamical Systems
34C29, 37G05
url https://arxiv.org/abs/2601.03147