Isometric rigidity of Wasserstein spaces over Euclidean spheres

Fuente: arXiv
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Autores principales: Gehér, György Pál, Hrušková, Aranka, Titkos, Tamás, Virosztek, Dániel
Formato: Preprint
Publicado: 2023
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author Gehér, György Pál
Hrušková, Aranka
Titkos, Tamás
Virosztek, Dániel
author_facet Gehér, György Pál
Hrušková, Aranka
Titkos, Tamás
Virosztek, Dániel
contents We study the structure of isometries of the quadratic Wasserstein space $\mathcal{W}_2\left(\mathbb{S}^n,\|\cdot\|\right)$ over the sphere endowed with the distance inherited from the norm of $\mathbb{R}^{n+1}$. We prove that $\mathcal{W}_2\left(\mathbb{S}^n,\|\cdot\|\right)$ is isometrically rigid, meaning that its isometry group is isomorphic to that of $\left(\mathbb{S}^n,\|\cdot\|\right)$. This is in striking contrast to the non-rigidity of its ambient space $\mathcal{W}_2\left(\mathbb{R}^n,\|\cdot\|\right)$ but in line with the rigidity of the geodesic space $\mathcal{W}_2\left(\mathbb{S}^n,\sphericalangle\right)$. One of the key steps of the proof is the use of mean squared error functions to mimic displacement interpolation in $\mathcal{W}_2\left(\mathbb{S}^n,\|\cdot\|\right)$. A major difficulty in proving rigidity for quadratic Wasserstein spaces is that one cannot use the Wasserstein potential technique. To illustrate its general power, we use it to prove isometric rigidity of $\mathcal{W}_p\left(\mathbb{S}^1, \|\cdot\|\right)$ for $1 \leq p<2.$
format Preprint
id arxiv_https___arxiv_org_abs_2308_05065
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Isometric rigidity of Wasserstein spaces over Euclidean spheres
Gehér, György Pál
Hrušková, Aranka
Titkos, Tamás
Virosztek, Dániel
Metric Geometry
Mathematical Physics
Functional Analysis
54E40, 46E27 (Primary) 60A10, 60B05 (Secondary)
We study the structure of isometries of the quadratic Wasserstein space $\mathcal{W}_2\left(\mathbb{S}^n,\|\cdot\|\right)$ over the sphere endowed with the distance inherited from the norm of $\mathbb{R}^{n+1}$. We prove that $\mathcal{W}_2\left(\mathbb{S}^n,\|\cdot\|\right)$ is isometrically rigid, meaning that its isometry group is isomorphic to that of $\left(\mathbb{S}^n,\|\cdot\|\right)$. This is in striking contrast to the non-rigidity of its ambient space $\mathcal{W}_2\left(\mathbb{R}^n,\|\cdot\|\right)$ but in line with the rigidity of the geodesic space $\mathcal{W}_2\left(\mathbb{S}^n,\sphericalangle\right)$. One of the key steps of the proof is the use of mean squared error functions to mimic displacement interpolation in $\mathcal{W}_2\left(\mathbb{S}^n,\|\cdot\|\right)$. A major difficulty in proving rigidity for quadratic Wasserstein spaces is that one cannot use the Wasserstein potential technique. To illustrate its general power, we use it to prove isometric rigidity of $\mathcal{W}_p\left(\mathbb{S}^1, \|\cdot\|\right)$ for $1 \leq p<2.$
title Isometric rigidity of Wasserstein spaces over Euclidean spheres
topic Metric Geometry
Mathematical Physics
Functional Analysis
54E40, 46E27 (Primary) 60A10, 60B05 (Secondary)
url https://arxiv.org/abs/2308.05065