The Michor-Mumford conjecture in Hilbertian H-type groups

Fuente: arXiv
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Autori principali: Magnani, Valentino, Tiberio, Daniele
Natura: Preprint
Pubblicazione: 2024
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author Magnani, Valentino
Tiberio, Daniele
author_facet Magnani, Valentino
Tiberio, Daniele
contents We introduce infinite dimensional Hilbertian H-type groups equipped with weak, graded, left invariant Riemannian metrics. For these Lie groups, we show that the vanishing of the geodesic distance and the local unboundedness of the sectional curvature coexist. The result validates a deep phenomenon conjectured in an influential 2005 paper by Michor and Mumford, namely, the vanishing of the geodesic distance is linked to the local unboundedness of the sectional curvature. We prove that degenerate geodesic distances appear for a large class of weak, left invariant Riemannian metrics. Their vanishing is rather surprisingly related to the infinite dimensional sub-Riemannian structure of Hilbertian H-type groups. The same class of weak Riemannian metrics yields the nonexistence of the Levi-Civita covariant derivative.
format Preprint
id arxiv_https___arxiv_org_abs_2404_04583
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Michor-Mumford conjecture in Hilbertian H-type groups
Magnani, Valentino
Tiberio, Daniele
Differential Geometry
Metric Geometry
We introduce infinite dimensional Hilbertian H-type groups equipped with weak, graded, left invariant Riemannian metrics. For these Lie groups, we show that the vanishing of the geodesic distance and the local unboundedness of the sectional curvature coexist. The result validates a deep phenomenon conjectured in an influential 2005 paper by Michor and Mumford, namely, the vanishing of the geodesic distance is linked to the local unboundedness of the sectional curvature. We prove that degenerate geodesic distances appear for a large class of weak, left invariant Riemannian metrics. Their vanishing is rather surprisingly related to the infinite dimensional sub-Riemannian structure of Hilbertian H-type groups. The same class of weak Riemannian metrics yields the nonexistence of the Levi-Civita covariant derivative.
title The Michor-Mumford conjecture in Hilbertian H-type groups
topic Differential Geometry
Metric Geometry
url https://arxiv.org/abs/2404.04583