Simultaneous linearization and centralizers of parabolic self-maps I: zero hyperbolic step

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Autori principali: Contreras, Manuel D., Díaz-Madrigal, Santiago, Gumenyuk, Pavel
Natura: Preprint
Pubblicazione: 2025
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author Contreras, Manuel D.
Díaz-Madrigal, Santiago
Gumenyuk, Pavel
author_facet Contreras, Manuel D.
Díaz-Madrigal, Santiago
Gumenyuk, Pavel
contents Let $φ:\mathbb D \to \mathbb D$ be a parabolic self-map of the unit disc $\mathbb D$ having zero hyperbolic step. We study holomorphic self-maps of $\mathbb D$ commuting with $φ$. In particular, we answer a question from Gentili and Vlacci (1994) by proving that $ψ\in\mathsf{Hol(\mathbb D,\mathbb D)}$ commutes with $φ$ if and only if the two self-maps have the same Denjoy-Wolff point and $ψ$ is a pseudo-iterate of $φ$ in the sense of Cowen. Moreover, we show that the centralizer of $φ$, i.e. the semigroup $\mathcal Z_\forall(φ):=\{ψ:ψ\circφ=φ\circψ\}$ is commutative. We also prove that if $φ$ is univalent, then all elements of $\mathcal Z_\forall(φ)$ are univalent as well, and if $φ$ is not univalent, then the identity map is an isolated point of $\mathcal Z_\forall(φ)$. The main tool is the machinery of simultaneous linearization, which we develop using holomorphic models for iteration of non-elliptic self-maps originating in works of Cowen and Pommerenke.
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id arxiv_https___arxiv_org_abs_2508_02809
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Simultaneous linearization and centralizers of parabolic self-maps I: zero hyperbolic step
Contreras, Manuel D.
Díaz-Madrigal, Santiago
Gumenyuk, Pavel
Complex Variables
Dynamical Systems
30C55, 37F44, 30D05
Let $φ:\mathbb D \to \mathbb D$ be a parabolic self-map of the unit disc $\mathbb D$ having zero hyperbolic step. We study holomorphic self-maps of $\mathbb D$ commuting with $φ$. In particular, we answer a question from Gentili and Vlacci (1994) by proving that $ψ\in\mathsf{Hol(\mathbb D,\mathbb D)}$ commutes with $φ$ if and only if the two self-maps have the same Denjoy-Wolff point and $ψ$ is a pseudo-iterate of $φ$ in the sense of Cowen. Moreover, we show that the centralizer of $φ$, i.e. the semigroup $\mathcal Z_\forall(φ):=\{ψ:ψ\circφ=φ\circψ\}$ is commutative. We also prove that if $φ$ is univalent, then all elements of $\mathcal Z_\forall(φ)$ are univalent as well, and if $φ$ is not univalent, then the identity map is an isolated point of $\mathcal Z_\forall(φ)$. The main tool is the machinery of simultaneous linearization, which we develop using holomorphic models for iteration of non-elliptic self-maps originating in works of Cowen and Pommerenke.
title Simultaneous linearization and centralizers of parabolic self-maps I: zero hyperbolic step
topic Complex Variables
Dynamical Systems
30C55, 37F44, 30D05
url https://arxiv.org/abs/2508.02809