Symmetrization and the rate of convergence of semigroups of holomorphic functions

Fuente: arXiv
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Auteurs principaux: Betsakos, Dimitrios, Christodoulou, Argyrios
Format: Preprint
Publié: 2025
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author Betsakos, Dimitrios
Christodoulou, Argyrios
author_facet Betsakos, Dimitrios
Christodoulou, Argyrios
contents Let $(ϕ_t)$, $t\ge 0$, be a semigroup of holomorphic self-maps of the unit disk $\mathbb{D}$. Let $Ω$ be its Koenigs domain and $τ\in \partial \mathbb{D}$ be its Denjoy-Wolff point. Suppose that $0\in Ω$ and let $Ω^\sharp$ be the Steiner symmetrization of $Ω$ with respect to the real axis. Consider the semigroup $(ϕ_t^\sharp)$ with Koenigs domain $Ω^\sharp$ and let $τ^\sharp$ be its Denjoy-Wolff point. We show that, up to a multiplicative constant, the rate of convergence of $(ϕ_t^\sharp)$ is slower than that of $(ϕ_t)$; that is, for every $t>0$, $|ϕ_t(0)-τ|\leq 4π\, |ϕ_t^\sharp(0)-τ^\sharp|$. The main tool for the proof is the harmonic measure.
format Preprint
id arxiv_https___arxiv_org_abs_2503_20447
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Symmetrization and the rate of convergence of semigroups of holomorphic functions
Betsakos, Dimitrios
Christodoulou, Argyrios
Complex Variables
Dynamical Systems
Let $(ϕ_t)$, $t\ge 0$, be a semigroup of holomorphic self-maps of the unit disk $\mathbb{D}$. Let $Ω$ be its Koenigs domain and $τ\in \partial \mathbb{D}$ be its Denjoy-Wolff point. Suppose that $0\in Ω$ and let $Ω^\sharp$ be the Steiner symmetrization of $Ω$ with respect to the real axis. Consider the semigroup $(ϕ_t^\sharp)$ with Koenigs domain $Ω^\sharp$ and let $τ^\sharp$ be its Denjoy-Wolff point. We show that, up to a multiplicative constant, the rate of convergence of $(ϕ_t^\sharp)$ is slower than that of $(ϕ_t)$; that is, for every $t>0$, $|ϕ_t(0)-τ|\leq 4π\, |ϕ_t^\sharp(0)-τ^\sharp|$. The main tool for the proof is the harmonic measure.
title Symmetrization and the rate of convergence of semigroups of holomorphic functions
topic Complex Variables
Dynamical Systems
url https://arxiv.org/abs/2503.20447