A 4-dimensional pseudo-Anosov homeomorphism

Fuente: arXiv
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Main Author: Martelli, Bruno
Format: Preprint
Published: 2025
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author Martelli, Bruno
author_facet Martelli, Bruno
contents We know from previous work with Italiano and Migliorini that there exists some hyperbolic 5-manifold that fibers over the circle. Here we build one example where the monodromy is a "pseudo-Anosov homeomorphism" of the 4-dimensional fiber, in a way that is surprisingly similar to the familiar and beautiful two-dimensional picture of Nielsen and Thurston for surfaces. This fact has various consequences: (1) There is a compact smooth 4-manifold $M$ such that no non-trivial class in $H_2(M)$ is represented by immersed tori, and infinitely many classes are represented by smoothly embedded genus two surfaces. (2) There is a compact locally CAT(0) space $Y$ such that $π_1(Y)$ is not hyperbolic and does not contain $\mathbb Z \times \mathbb Z$. The latter answers a question of Gromov, known as the Closing Flat Problem.
format Preprint
id arxiv_https___arxiv_org_abs_2511_10530
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A 4-dimensional pseudo-Anosov homeomorphism
Martelli, Bruno
Geometric Topology
Differential Geometry
Dynamical Systems
We know from previous work with Italiano and Migliorini that there exists some hyperbolic 5-manifold that fibers over the circle. Here we build one example where the monodromy is a "pseudo-Anosov homeomorphism" of the 4-dimensional fiber, in a way that is surprisingly similar to the familiar and beautiful two-dimensional picture of Nielsen and Thurston for surfaces. This fact has various consequences: (1) There is a compact smooth 4-manifold $M$ such that no non-trivial class in $H_2(M)$ is represented by immersed tori, and infinitely many classes are represented by smoothly embedded genus two surfaces. (2) There is a compact locally CAT(0) space $Y$ such that $π_1(Y)$ is not hyperbolic and does not contain $\mathbb Z \times \mathbb Z$. The latter answers a question of Gromov, known as the Closing Flat Problem.
title A 4-dimensional pseudo-Anosov homeomorphism
topic Geometric Topology
Differential Geometry
Dynamical Systems
url https://arxiv.org/abs/2511.10530