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Main Authors: Belk, James, Forrest, Bradley
Format: Preprint
Published: 2023
Subjects:
Online Access:https://arxiv.org/abs/2310.17442
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author Belk, James
Forrest, Bradley
author_facet Belk, James
Forrest, Bradley
contents We develop a theory of quasisymmetries for finitely ramified fractals, with applications to finitely ramified Julia sets. We prove that certain finitely ramified fractals admit a naturally defined class of "undistorted metrics" that are all quasi-equivalent. As a result, piecewise-defined homeomorphisms of such a fractal that locally preserve the cell structure are quasisymmetries. This immediately gives a solution to the quasisymmetric uniformization problem for topologically rigid fractals such as the Sierpiński triangle. We show that our theory applies to many finitely ramified Julia sets, and we prove that any connected Julia set for a hyperbolic unicritical polynomial has infinitely many quasisymmetries, generalizing a result of Lyubich and Merenkov. We also prove that the quasisymmetry group of the Julia set for the rational function $1-z^{-2}$ is infinite, and we show that the quasisymmetry groups for the Julia sets of a broad class of polynomials contain Thompson's group $F$.
format Preprint
id arxiv_https___arxiv_org_abs_2310_17442
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Quasisymmetries of finitely ramified Julia sets
Belk, James
Forrest, Bradley
Dynamical Systems
Group Theory
37F10 (Primary) 20F38, 28A80, 30C62 (Secondary)
We develop a theory of quasisymmetries for finitely ramified fractals, with applications to finitely ramified Julia sets. We prove that certain finitely ramified fractals admit a naturally defined class of "undistorted metrics" that are all quasi-equivalent. As a result, piecewise-defined homeomorphisms of such a fractal that locally preserve the cell structure are quasisymmetries. This immediately gives a solution to the quasisymmetric uniformization problem for topologically rigid fractals such as the Sierpiński triangle. We show that our theory applies to many finitely ramified Julia sets, and we prove that any connected Julia set for a hyperbolic unicritical polynomial has infinitely many quasisymmetries, generalizing a result of Lyubich and Merenkov. We also prove that the quasisymmetry group of the Julia set for the rational function $1-z^{-2}$ is infinite, and we show that the quasisymmetry groups for the Julia sets of a broad class of polynomials contain Thompson's group $F$.
title Quasisymmetries of finitely ramified Julia sets
topic Dynamical Systems
Group Theory
37F10 (Primary) 20F38, 28A80, 30C62 (Secondary)
url https://arxiv.org/abs/2310.17442