Julia sets of rational maps with rotational symmetries

Fuente: arXiv
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Hauptverfasser: Nayak, Tarakanta, Pal, Soumen
Format: Preprint
Veröffentlicht: 2024
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author Nayak, Tarakanta
Pal, Soumen
author_facet Nayak, Tarakanta
Pal, Soumen
contents By a symmetry of the Julia set of a polynomial, also referred as polynomial Julia set, we mean an Euclidean isometry preserving the Julia set. Each such symmetry is in fact a rotation about the centroid of the polynomial. In this article, a survey of the symmetries of polynomial Julia sets is made. Then the Euclidean isometries preserving the Julia set of rational maps are considered. A rotation preserving the Julia set of a rational map is called a rotational symmetry of its Julia set. A sufficient condition is provided for a rational map to have rotational symmetries whenever the rational map has an exceptional point. Two classes of rational maps are provided whose Julia sets have rotational symmetries of finite orders. Using this, it is proved that $ z\mapsto μz$ where $μ^{m+n}=1$ is a rotational symmetry of the McMullen map $ z^m+\fracλ{z^n}$ for all $m,n$ with $m\geq 2$ and $λ\in \mathbb{C}\setminus \{0\}$. Assuming that a normalized polynomial has a simple root at the origin, it is shown that the groups of the rotational symmetries of the polynmial coincide with that of its Newton's method and Chebyshev's method.
format Preprint
id arxiv_https___arxiv_org_abs_2402_07137
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Julia sets of rational maps with rotational symmetries
Nayak, Tarakanta
Pal, Soumen
Dynamical Systems
By a symmetry of the Julia set of a polynomial, also referred as polynomial Julia set, we mean an Euclidean isometry preserving the Julia set. Each such symmetry is in fact a rotation about the centroid of the polynomial. In this article, a survey of the symmetries of polynomial Julia sets is made. Then the Euclidean isometries preserving the Julia set of rational maps are considered. A rotation preserving the Julia set of a rational map is called a rotational symmetry of its Julia set. A sufficient condition is provided for a rational map to have rotational symmetries whenever the rational map has an exceptional point. Two classes of rational maps are provided whose Julia sets have rotational symmetries of finite orders. Using this, it is proved that $ z\mapsto μz$ where $μ^{m+n}=1$ is a rotational symmetry of the McMullen map $ z^m+\fracλ{z^n}$ for all $m,n$ with $m\geq 2$ and $λ\in \mathbb{C}\setminus \{0\}$. Assuming that a normalized polynomial has a simple root at the origin, it is shown that the groups of the rotational symmetries of the polynmial coincide with that of its Newton's method and Chebyshev's method.
title Julia sets of rational maps with rotational symmetries
topic Dynamical Systems
url https://arxiv.org/abs/2402.07137