Connectivity properties of the Schur-Horn map for real Grassmannians

Fuente: arXiv
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Auteur principal: Mare, Augustin-Liviu
Format: Preprint
Publié: 2023
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author Mare, Augustin-Liviu
author_facet Mare, Augustin-Liviu
contents To any $V$ in the Grassmannian ${\rm Gr}_k({\mathbb R}^n)$ of $k$-dimensional vector subspaces in ${\mathbb R}^n$ one can associate the diagonal entries of the ($n\times n$) matrix corresponding to the orthogonal projection of ${\mathbb R}^n$ to $V$. One obtains a map ${\rm Gr}_k({\mathbb R}^n)\to {\mathbb R}^n$ (the Schur-Horn map). The main result of this paper is a criterion for pre-images of vectors in ${\mathbb R}^n$ to be connected. This will allow us to deduce connectivity criteria for a certain class of subspaces of the real Stiefel manifold which arise naturally in frame theory. We extend in this way results of Cahill, Mixon, and Strawn.
format Preprint
id arxiv_https___arxiv_org_abs_2309_11596
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Connectivity properties of the Schur-Horn map for real Grassmannians
Mare, Augustin-Liviu
Differential Geometry
14M15, 53C42, 53D20
To any $V$ in the Grassmannian ${\rm Gr}_k({\mathbb R}^n)$ of $k$-dimensional vector subspaces in ${\mathbb R}^n$ one can associate the diagonal entries of the ($n\times n$) matrix corresponding to the orthogonal projection of ${\mathbb R}^n$ to $V$. One obtains a map ${\rm Gr}_k({\mathbb R}^n)\to {\mathbb R}^n$ (the Schur-Horn map). The main result of this paper is a criterion for pre-images of vectors in ${\mathbb R}^n$ to be connected. This will allow us to deduce connectivity criteria for a certain class of subspaces of the real Stiefel manifold which arise naturally in frame theory. We extend in this way results of Cahill, Mixon, and Strawn.
title Connectivity properties of the Schur-Horn map for real Grassmannians
topic Differential Geometry
14M15, 53C42, 53D20
url https://arxiv.org/abs/2309.11596