Homotopy Hubbard Trees for post-singularly finite exponential maps

Fuente: arXiv
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Main Authors: Pfrang, David, Rothgang, Michael, Schleicher, Dierk
Format: Preprint
Published: 2018
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_version_ 1866916923808153600
author Pfrang, David
Rothgang, Michael
Schleicher, Dierk
author_facet Pfrang, David
Rothgang, Michael
Schleicher, Dierk
contents We extend the concept of a Hubbard tree, well established and useful in the theory of polynomial dynamics, to the dynamics of transcendental entire functions. We show that Hubbard trees in the strict traditional sense, as invariant compact trees embedded in $\mathbb{C}$, do not exist even for post-singularly finite exponential maps; the difficulty lies in the existence of asymptotic values. We therefore introduce the concept of a Homotopy Hubbard Tree that takes care of these difficulties. Specifically for the family of exponential maps, we show that every post-singularly finite map has a Homotopy Hubbard tree that is unique up to homotopy, and we show that post-singulary finite exponential maps can be classified in terms of Homotopy Hubbard Trees, using a transcendental analogue of Thurston's topological characterization theorem of rational maps.
format Preprint
id arxiv_https___arxiv_org_abs_1812_11831
institution arXiv
publishDate 2018
record_format arxiv
spellingShingle Homotopy Hubbard Trees for post-singularly finite exponential maps
Pfrang, David
Rothgang, Michael
Schleicher, Dierk
Dynamical Systems
37B10, 37E25, 37F10, 37F20, 37F46
We extend the concept of a Hubbard tree, well established and useful in the theory of polynomial dynamics, to the dynamics of transcendental entire functions. We show that Hubbard trees in the strict traditional sense, as invariant compact trees embedded in $\mathbb{C}$, do not exist even for post-singularly finite exponential maps; the difficulty lies in the existence of asymptotic values. We therefore introduce the concept of a Homotopy Hubbard Tree that takes care of these difficulties. Specifically for the family of exponential maps, we show that every post-singularly finite map has a Homotopy Hubbard tree that is unique up to homotopy, and we show that post-singulary finite exponential maps can be classified in terms of Homotopy Hubbard Trees, using a transcendental analogue of Thurston's topological characterization theorem of rational maps.
title Homotopy Hubbard Trees for post-singularly finite exponential maps
topic Dynamical Systems
37B10, 37E25, 37F10, 37F20, 37F46
url https://arxiv.org/abs/1812.11831