Critically fixed Thurston maps: classification, recognition, and twisting

Fuente: arXiv
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Hauptverfasser: Hlushchanka, Mikhail, Prochorov, Nikolai
Format: Preprint
Veröffentlicht: 2022
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author Hlushchanka, Mikhail
Prochorov, Nikolai
author_facet Hlushchanka, Mikhail
Prochorov, Nikolai
contents An orientation-preserving branched covering map $f\colon S^2 \to S^2$ is called a critically fixed Thurston map if $f$ fixes each of its critical points. It was recently shown that there is an explicit one-to-one correspondence between Möbius conjugacy classes of critically fixed rational maps and isomorphism classes of planar embedded connected graphs. In the paper, we generalize this result to the whole family of critically fixed Thurston maps. Namely, we show that each critically fixed Thurston map $f$ is obtained by applying the blow-up operation, introduced by Kevin Pilgrim and Tan Lei, to a pair $(G,φ)$, where $G$ is a planar embedded graph in $S^2$ without isolated vertices and $φ$ is an orientation-preserving homeomorphism of $S^2$ that fixes each vertex of $G$. This result allows us to provide a classification of combinatorial equivalence classes of critically fixed Thurston maps. We also develop an algorithm that reconstructs (up to isotopy) the pair $(G,φ)$ associated with a critically fixed Thurston map $f$. Finally, we solve some special instances of the twisting problem for the family of critically fixed Thurston maps obtained by blowing up pairs $(G, \mathrm{id}_{S^2})$.
format Preprint
id arxiv_https___arxiv_org_abs_2212_14759
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Critically fixed Thurston maps: classification, recognition, and twisting
Hlushchanka, Mikhail
Prochorov, Nikolai
Dynamical Systems
37F20, 37F10
An orientation-preserving branched covering map $f\colon S^2 \to S^2$ is called a critically fixed Thurston map if $f$ fixes each of its critical points. It was recently shown that there is an explicit one-to-one correspondence between Möbius conjugacy classes of critically fixed rational maps and isomorphism classes of planar embedded connected graphs. In the paper, we generalize this result to the whole family of critically fixed Thurston maps. Namely, we show that each critically fixed Thurston map $f$ is obtained by applying the blow-up operation, introduced by Kevin Pilgrim and Tan Lei, to a pair $(G,φ)$, where $G$ is a planar embedded graph in $S^2$ without isolated vertices and $φ$ is an orientation-preserving homeomorphism of $S^2$ that fixes each vertex of $G$. This result allows us to provide a classification of combinatorial equivalence classes of critically fixed Thurston maps. We also develop an algorithm that reconstructs (up to isotopy) the pair $(G,φ)$ associated with a critically fixed Thurston map $f$. Finally, we solve some special instances of the twisting problem for the family of critically fixed Thurston maps obtained by blowing up pairs $(G, \mathrm{id}_{S^2})$.
title Critically fixed Thurston maps: classification, recognition, and twisting
topic Dynamical Systems
37F20, 37F10
url https://arxiv.org/abs/2212.14759