Transverse Spheres in Flag Manifolds

Fuente: arXiv
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Hauptverfasser: Evans, Parker, Riestenberg, J. Maxwell
Format: Preprint
Veröffentlicht: 2025
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author Evans, Parker
Riestenberg, J. Maxwell
author_facet Evans, Parker
Riestenberg, J. Maxwell
contents For some partial flag manifolds of semisimple real Lie groups, including many full flag manifolds, transverse circles are known to be locally maximally transverse. We complete the classification of all partial flag manifolds of split real Lie groups with this property. As a consequence, $\{7\}$-Anosov subgroups of split $E_7$ are virtually free or surface groups. On the other hand, using spinors, we find transverse spheres of arbitrarily large dimension in certain full flag manifolds of Cartan-Killing types $A,B,D$. These transverse spheres are verified to be maximally transverse with tools from topological $K$-theory. The aforementioned classification follows from constructions of transverse $m$-spheres, $m \geq 2$, that complement the previously known restrictions as well as the new $E_7$ restriction. Additionally, when $G$ is split of type $G_2, B_3,$ or $D_4$, the full flag manifold admits a fibration by maximally transverse 3-spheres.
format Preprint
id arxiv_https___arxiv_org_abs_2507_19306
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Transverse Spheres in Flag Manifolds
Evans, Parker
Riestenberg, J. Maxwell
Geometric Topology
Differential Geometry
14M15 (Primary) 57T20, 19L64, 22E40 (Secondary)
For some partial flag manifolds of semisimple real Lie groups, including many full flag manifolds, transverse circles are known to be locally maximally transverse. We complete the classification of all partial flag manifolds of split real Lie groups with this property. As a consequence, $\{7\}$-Anosov subgroups of split $E_7$ are virtually free or surface groups. On the other hand, using spinors, we find transverse spheres of arbitrarily large dimension in certain full flag manifolds of Cartan-Killing types $A,B,D$. These transverse spheres are verified to be maximally transverse with tools from topological $K$-theory. The aforementioned classification follows from constructions of transverse $m$-spheres, $m \geq 2$, that complement the previously known restrictions as well as the new $E_7$ restriction. Additionally, when $G$ is split of type $G_2, B_3,$ or $D_4$, the full flag manifold admits a fibration by maximally transverse 3-spheres.
title Transverse Spheres in Flag Manifolds
topic Geometric Topology
Differential Geometry
14M15 (Primary) 57T20, 19L64, 22E40 (Secondary)
url https://arxiv.org/abs/2507.19306