On iterates of rational functions with maximal number of critical values

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Bibliographic Details
Title: On iterates of rational functions with maximal number of critical values
Authors: Pakovich, Fedor
Source: Journal d'Analyse Mathématique. 156:213-251
Publication Status: Preprint
Publisher Information: Springer Science and Business Media LLC, 2025.
Publication Year: 2025
Subject Terms: Mathematics - Complex Variables, FOS: Mathematics, Dynamical Systems (math.DS), Mathematics - Dynamical Systems, 0101 mathematics, Complex Variables (math.CV), 01 natural sciences
Description: Let F be a rational function of one complex variable of degree m ≥ 2. The function F is called simple if for every z ∈ ℂℙ1 the preimage F −1{z} contains at least m − 1 points. We show that if F is a simple rational function of degree m ≥ 4 and F ◦l = G r ◦ G r−1 ◦ ⋯ ◦ G 1, l ≥ 1, is a decomposition of an iterate of F into a composition of indecomposable rational functions, then r = l and there exist Möbius transformations μ i , 1 ≤ i ≤ r − 1, such that G r = F ◦ μ r−1, G i = μ i −1 ◦ F ◦ μ i−1, 1 < i < r, and G 1 = μ 1 −1 ◦ F. As applications, we solve a number of problems in complex and arithmetic dynamics for “general” rational functions.
Document Type: Article
Language: English
ISSN: 1565-8538
0021-7670
DOI: 10.1007/s11854-025-0386-z
DOI: 10.48550/arxiv.2107.05963
Access URL: http://arxiv.org/abs/2107.05963
Rights: CC BY
arXiv Non-Exclusive Distribution
Accession Number: edsair.doi.dedup.....f02d29f105878913709c81165160f83f
Database: OpenAIRE
Description
Abstract:Let F be a rational function of one complex variable of degree m ≥ 2. The function F is called simple if for every z ∈ ℂℙ1 the preimage F −1{z} contains at least m − 1 points. We show that if F is a simple rational function of degree m ≥ 4 and F ◦l = G r ◦ G r−1 ◦ ⋯ ◦ G 1, l ≥ 1, is a decomposition of an iterate of F into a composition of indecomposable rational functions, then r = l and there exist Möbius transformations μ i , 1 ≤ i ≤ r − 1, such that G r = F ◦ μ r−1, G i = μ i −1 ◦ F ◦ μ i−1, 1 < i < r, and G 1 = μ 1 −1 ◦ F. As applications, we solve a number of problems in complex and arithmetic dynamics for “general” rational functions.
ISSN:15658538
00217670
DOI:10.1007/s11854-025-0386-z