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For a two-dimensional surface in the four-dimensional Euclidean space we introduce an invariant linear map of Weingarten type in the tangent space of the surface, which generates two invariants k and kappa. The condition k = kappa = 0…

Differential Geometry · Mathematics 2008-04-29 Georgi Ganchev , Velichka Milousheva

We define a general notion of a smooth invariant (central) ergodic measure on the space of paths of an $N$-graded graph (Bratteli diagram). It is based on the notion of standardness of the tail filtration in the space of paths, and the…

Representation Theory · Mathematics 2013-12-30 Anatoly Vershik

We study homogeneous curves in generalized flag manifolds $G/K$ with $G_2$-type $t$-roots, which are geodesics with respect to each $G$-invariant metric on $G/K$. These curves are called equigeodesics. The tangent space of such flag…

Differential Geometry · Mathematics 2020-09-08 Marina Statha

In this paper, we investigate the geometric invariant properties of a normal curve on a smooth immersed surface under conformal transformation. We obtain an invariant-sufficient condition for the conformal image of a normal curve. We also…

General Mathematics · Mathematics 2019-08-12 Mohamd Saleem Lone

Our aim is to study invariant hypersurfaces immersed in the Euclidean space $\mathbb{R}^{n+1}$, whose mean curvature is given as a linear function in the unit sphere $\mathbb{S}^n$ depending on its Gauss map. These hypersurfaces are closely…

Differential Geometry · Mathematics 2019-08-21 Antonio Bueno , Irene Ortiz

We study the global geometry of families of tubes of constant mean curvature invariant under screw-motions in homogeneous $\mathbb{E}(\kappa,\tau)$-spaces. In particular, we study embeddedness and prove a foliation result. Moreover, we…

Differential Geometry · Mathematics 2024-12-23 Philipp Käse , Francisco Torralbo

A Finsler space $(M,F)$ is called flag-wise positively curved, if for any $x\in M$ and any tangent plane $\mathbf{P}\subset T_xM$, we can find a nonzero vector $y\in \mathbf{P}$, such that the flag curvature $K^F(x,y, \mathbf{P})>0$. Though…

Differential Geometry · Mathematics 2016-06-09 Ming Xu

In the elastic shape analysis approach to shape matching and object classification, plane curves are represented as points in an infinite-dimensional Riemannian manifold, wherein shape dissimilarity is measured by geodesic distance. A…

Differential Geometry · Mathematics 2018-07-11 Tom Needham

Let $\gamma$ be a filling curve on a topological surface $\Sigma$ of genus $g \geq 2$. The inf invariant of $\gamma$, denoted $m_{\gamma}$, is the infimum of the length function on the space of marked hyperbolic structures on $\Sigma$. This…

Geometric Topology · Mathematics 2025-08-13 Ara Basmajian , Sayantika Mondal

In the present article we compute the flag curvature of a special type of invariant Kropina metrics on homogeneous spaces.

Differential Geometry · Mathematics 2015-07-09 H. R. Salimi Moghaddam

In this manuscript we consider non-degenerate surfaces $\Sigma^2$ immersed in a 3-dimensional homogeneous space $\mathbb{L}^3(\kappa,\tau)$ endowed with two different metrics, the one induced by the Riemannian metric of…

Differential Geometry · Mathematics 2024-05-01 Alma L. Albujer , Fábio R. dos Santos

This paper studies a specific metric on plane curves that has the property of being isometric to classical manifold (sphere, complex projective, Stiefel, Grassmann) modulo change of parametrization, each of these classical manifolds being…

Differential Geometry · Mathematics 2008-05-05 Peter W. Michor , David Mumford , Jayant Shah , Laurent Younes

In the tangent plane at any point of a surface in the four-dimensional Euclidean space we consider an invariant linear map of Weingarten-type and find a geometrically determined moving frame field. Writing derivative formulas of Frenet-type…

Differential Geometry · Mathematics 2011-05-18 Georgi Ganchev , Velichka Milousheva

In this paper we study flag curvature of invariant $(\alpha,\beta)$-metrics of the form $\frac{(\alpha+\beta)^2}{\alpha}$ on homogeneous spaces and Lie groups. We give a formula for flag curvature of invariant metrics of the form…

Differential Geometry · Mathematics 2015-07-08 H. R. Salimi Moghaddam

We show the flexibility of the metric entropy and obtain additional restrictions on the topological entropy of geodesic flow on closed surfaces of negative Euler characteristic with smooth non-positively curved Riemannian metrics with fixed…

Dynamical Systems · Mathematics 2020-08-07 Thomas Barthelmé , Alena Erchenko

Let $\Sigma$ denote a closed surface with constant mean curvature in $\mathbb{G}^3$, a 3-dimensional Lie group equipped with a bi-invariant metric. For such surfaces, there is a harmonic Gauss map which maps values to the unit sphere within…

Differential Geometry · Mathematics 2026-01-22 Alcides de Carvalho , Marcos P. Cavalcante , Wagner Costa-Filho , Darlan de Oliveira

In the shape analysis approach to computer vision problems, one treats shapes as points in an infinite-dimensional Riemannian manifold, thereby facilitating algorithms for statistical calculations such as geodesic distance between shapes…

Differential Geometry · Mathematics 2018-03-30 Sebastian Kurtek , Tom Needham

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

We define a computable topological invariant $\mu(\gamma)$ for generic closed planar regular curves $\gamma$, which gives an effective lower bound for the number of inflection points on a given generic closed planar curve. Using it, we…

Differential Geometry · Mathematics 2011-03-18 Shuntaro Ohno , Tetsuya Ozawa , Masaaki Umehara

This article provides an overview of various notions of shape spaces, including the space of parametrized and unparametrized curves, the space of immersions, the diffeomorphism group and the space of Riemannian metrics. We discuss the…

Differential Geometry · Mathematics 2014-10-07 Martin Bauer , Martins Bruveris , Peter W. Michor