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Autori principali: Pfaff, Catherine Eva, Tsang, Chi Cheuk
Natura: Preprint
Pubblicazione: 2025
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Accesso online:https://arxiv.org/abs/2503.16360
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author Pfaff, Catherine Eva
Tsang, Chi Cheuk
author_facet Pfaff, Catherine Eva
Tsang, Chi Cheuk
contents We show that the axis bundle of a nongeometric fully irreducible outer automorphism admits a canonical "cubist" decomposition into branched cubes that fit together with special combinatorics. From this structure, we locate a canonical finite collection of periodic fold lines in each axis bundle. This can be considered as an analogue of results of Hamenstädt and Agol from the surface setting, which state that the set of trivalent train tracks carrying the unstable lamination of a pseudo-Anosov map can be given the structure of a CAT(0) cube complex, and that there is a canonical periodic fold line in this cube complex. This work also gives an answer to questions of Handel-Mosher and Bridson-Vogtmann regarding the geometry of the axis bundle and a solution of a new flavor to the fully irreducible conjugacy problem in $\mathrm{Out}(F_r)$.
format Preprint
id arxiv_https___arxiv_org_abs_2503_16360
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A "cubist" decomposition of the Handel-Mosher axis bundle
Pfaff, Catherine Eva
Tsang, Chi Cheuk
Group Theory
Geometric Topology
We show that the axis bundle of a nongeometric fully irreducible outer automorphism admits a canonical "cubist" decomposition into branched cubes that fit together with special combinatorics. From this structure, we locate a canonical finite collection of periodic fold lines in each axis bundle. This can be considered as an analogue of results of Hamenstädt and Agol from the surface setting, which state that the set of trivalent train tracks carrying the unstable lamination of a pseudo-Anosov map can be given the structure of a CAT(0) cube complex, and that there is a canonical periodic fold line in this cube complex. This work also gives an answer to questions of Handel-Mosher and Bridson-Vogtmann regarding the geometry of the axis bundle and a solution of a new flavor to the fully irreducible conjugacy problem in $\mathrm{Out}(F_r)$.
title A "cubist" decomposition of the Handel-Mosher axis bundle
topic Group Theory
Geometric Topology
url https://arxiv.org/abs/2503.16360