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The increasing application of deep-learning is accompanied by a shift towards highly non-linear statistical models. In terms of their geometry it is natural to identify these models with Riemannian manifolds. The further analysis of the…

Statistics Theory · Mathematics 2020-06-23 Patrick Michl

We study curvature invariants of a sub-Riemannian manifold (i.e., a manifold with a Riemannian metric on a non-holonomic distribution) related to mutual curvature of several pairwise orthogonal subspaces of the distribution, and prove…

Differential Geometry · Mathematics 2022-12-27 Vladimir Rovenski

In this paper we study pseudo-Riemannian spaces with a degenerate curvature structure i.e. there exists a continuous family of metrics having identical polynomial curvature invariants. We approach this problem by utilising an idea coming…

Mathematical Physics · Physics 2015-12-09 Sigbjorn Hervik , Anders Haarr , Kei Yamamoto

This paper proposes an original Riemmanian geometry for low-rank structured elliptical models, i.e., when samples are elliptically distributed with a covariance matrix that has a low-rank plus identity structure. The considered geometry is…

Differential Geometry · Mathematics 2020-01-07 Florent Bouchard , Arnaud Breloy , Guillaume Ginolhac , Alexandre Renaux , Frédéric Pascal

We prove that if $(M,g)$ is a topological 3-ball with a $C^4$-smooth Riemannian metric $g$, and mean-convex boundary $\partial M$ then knowledge of least areas circumscribed by simple closed curves $\gamma \subset \partial M$ uniquely…

Differential Geometry · Mathematics 2021-03-26 Spyros Alexakis , Tracey Balehowsky , Adrian Nachman

Correlation matrices are fundamental summaries of functional brain networks, yet standard analyses often treat entries independently, ignoring the curved geometry of correlation space. Existing geometric methods frequently lack closed-form…

Machine Learning · Computer Science 2026-05-22 Mario Severino , Manuela Moretto , Robert A. McCutcheon , Mattia Veronese

Isotropic almost complex structures induce a class of Riemannian metrics on tangent bundle of a Riemannian manifold. In this paper the curvature tensors of these metrics will be calculated.

Differential Geometry · Mathematics 2017-04-24 Amir Baghban , Esmaeil Abedi

In this paper we study geometries on the manifold of curves. We define a manifold $M$ where objects $c\in M$ are curves, which we parameterize as $c:S^1\to \real^n$ ($n\ge 2$, $S^1$ is the circle). Given a curve $c$, we define the tangent…

Differential Geometry · Mathematics 2007-05-23 A. Yezzi , A. Mennucci

Within a framework of noncommutative geometry, we develop an analogue of (pseudo) Riemannian geometry on finite and discrete sets. On a finite set, there is a counterpart of the continuum metric tensor with a simple geometric…

General Relativity and Quantum Cosmology · Physics 2009-10-31 A. Dimakis , F. Muller-Hoissen

Shape spaces are fundamental in a variety of applications including image registration, morphing, matching, interpolation, and shape optimization. In this work, we consider two-dimensional shapes represented by triangular meshes of a given…

Numerical Analysis · Mathematics 2022-01-11 Roland Herzog , Estefanía Loayza-Romero

Roundness of metric spaces was introduced by Per Enflo as a tool to study uniform structures of linear topological spaces. The present paper investigates geometric and topological properties detected by the roundness of general metric…

Metric Geometry · Mathematics 2007-05-23 J. -F. Lafont , S. Prassidis

This paper is concerned with the computation of an optimal matching between two manifold-valued curves. Curves are seen as elements of an infinite-dimensional manifold and compared using a Riemannian metric that is invariant under the…

Differential Geometry · Mathematics 2024-01-11 Alice Le Brigant , Marc Arnaudon , Frédéric Barbaresco

Riemannian neural networks, which extend deep learning techniques to Riemannian spaces, have gained significant attention in machine learning. To better classify the manifold-valued features, researchers have started extending Euclidean…

Machine Learning · Computer Science 2024-10-03 Ziheng Chen , Yue Song , Rui Wang , Xiaojun Wu , Nicu Sebe

What is the shortest path between two data points lying in a high-dimensional space? While the answer is trivial in Euclidean geometry, it becomes significantly more complex when the data lies on a curved manifold -- requiring a Riemannian…

Machine Learning · Computer Science 2025-11-04 Louis Béthune , David Vigouroux , Yilun Du , Rufin VanRullen , Thomas Serre , Victor Boutin

We show that any Riemannian metric conformal to the round metric on $S^n$, for $n\geq 4$, arises as a limit of a sequence of Riemannian metrics of positive scalar curvature on $S^n$ in the sense of uniform convergence of Riemannian…

Differential Geometry · Mathematics 2024-11-19 Man-Chun Lee , Peter M. Topping

In this article we study stability and compactness w.r.t. measured Gromov-Hausdorff convergence of smooth metric measure spaces with integral Ricci curvature bounds. More precisely, we prove that a sequence of $n$-dimensional Riemannian…

Differential Geometry · Mathematics 2020-07-29 Christian Ketterer

We introduce the concept of ODD ('$\mathbf{O}$rthogonally $\mathbf{D}$egenerating on a $\mathbf{D}$ivisor') Riemannian metrics on real analytic manifolds $M$. These semipositive symmetric $2$-tensors may degenerate on a finite collection of…

Differential Geometry · Mathematics 2022-11-28 Lukas Braun

Motivated by the application to spacetimes of general relativity we investigate the geometry and regularity of Lorentzian manifolds under certain curvature and volume bounds. We establish several injectivity radius estimates at a point or…

Analysis of PDEs · Mathematics 2007-05-23 Bing-Long Chen , Philippe G. LeFloch

The article is devoted to the study of mappings with finite distortion in metric spaces. Analogues of results relating to equicontinuity and normality of families of quasiregular mappings are obtained. It is proved that the indicated…

Complex Variables · Mathematics 2019-01-23 Evgeny Sevost'yanov , Sergei Skvortsov , Evgeniy Petrov

In this paper, we derived biharmonic equations for pseudo-Riemannian submanifolds of pseudo-Riemannian manifolds which includes the biharmonic equations for submanifolds of Riemannian manifolds as a special case. As applications, we proved…

Differential Geometry · Mathematics 2015-12-09 Yuxin Dong , Ye-Lin Ou