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The geodesic orbit property has been studied intensively for Riemannian manifolds. Geodesic orbit spaces are homogeneous and allow simplifications of many structural questions using the Lie algebra of the isometry group. Weakly symmetric…

Differential Geometry · Mathematics 2021-10-26 Zhiqi Chen , Joseph A. Wolf , Shaoxiang Zhang

We study locally conformal calibrated $G_2$-structures whose underlying Riemannian metric is Einstein, showing that in the compact case the scalar curvature cannot be positive. As a consequence, a compact homogeneous $7$-manifold cannot…

Differential Geometry · Mathematics 2020-08-11 Anna Fino , Alberto Raffero

We complete our recent classification of compact inner symmetric spaces with weakly complex tangent bundle by filling up a case which was left open, and extend this classification to the larger category of compact homogeneous spaces with…

Differential Geometry · Mathematics 2019-01-08 Andrei Moroianu , Uwe Semmelmann

A topological space ${\mathcal X}$ is reversible iff each continuous bijection (condensation) $f: {\mathcal X} \rightarrow {\mathcal X}$ is a homeomorphism; weakly reversible iff whenever ${\mathcal Y}$ is a space and there are…

General Topology · Mathematics 2024-12-11 Miloš S. Kurilić

The goal of this article is to study the geometry of Bach-flat noncompact steady quasi-Einstein manifolds. We show that a Bach-flat noncompact steady quasi-Einstein manifold $(M^{n},\,g)$ with positive Ricci curvature such that its…

Differential Geometry · Mathematics 2016-12-15 M. Ranieri , E. Ribeiro

We show that an enlargeable Riemannian metric on a (possibly nonspin) manifold cannot have uniformly positive scalar curvature. This extends a well-known result of Gromov and Lawson to the nonspin setting. We also prove that every…

Geometric Topology · Mathematics 2021-01-01 Simone Cecchini , Thomas Schick

We consider the Einstein constraints on asymptotically euclidean manifolds $M$ of dimension $n \geq 3$ with sources of both scaled and unscaled types. We extend to asymptotically euclidean manifolds the constructive method of proof of…

General Relativity and Quantum Cosmology · Physics 2012-08-27 Yvonne Choquet-Bruhat , James Isenberg , James W. York,

Hypersurfaces embedded in conformal manifolds appear frequently as boundary data in boundary-value problems in cosmology and string theory. Viewed as the non-null conformal infinity of a spacetime, we consider hypersurfaces embedded in a…

Differential Geometry · Mathematics 2023-02-06 Samuel Blitz

The two-jet of the curvature tensor at some point of a pseudo-Riemannian manifold is called Einstein if the Ricci tensor is a multiple of the metric tensor at the given point and additionally its first two covariant derivatives vanish…

Differential Geometry · Mathematics 2015-12-15 Tillmann Jentsch

By revisiting the notion of generalized second fundamental form originally introduced by Hutchinson for a special class of integral varifolds, we define a weak curvature tensor that is particularly well-suited for being extended to general…

Classical Analysis and ODEs · Mathematics 2020-01-29 Blanche Buet , Gian Paolo Leonardi , Simon Masnou

We study generalized Killing spinors on compact Einstein manifolds with positive scalar curvature. This problem is related to the existence compact Einstein hypersurfaces in manifolds with parallel spinors, or equivalently, in Riemannian…

Differential Geometry · Mathematics 2019-01-08 Andrei Moroianu , Uwe Semmelmann

In this paper, we prove a classification theorem for the stable compact minimal submanifolds of the Riemannian product of an $m_1$-dimensional ($m_1\geq3$) hypersurface $M_1$ in the Euclidean space and any Riemannian manifold $M_2$, when…

Differential Geometry · Mathematics 2012-10-01 Hang Chen , Xianfeng Wang

Restrictions are obtained on the topology of a compact divergence-free null hypersurface in a four-dimensional Lorentzian manifold whose Ricci tensor is zero or satisfies some weaker conditions. This is done by showing that each null…

dg-ga · Mathematics 2008-02-03 Alan D. Rendall

In this paper, almost product-like Riemannian manifolds are investigated. Basic properties on tangential hypersurfaces of almost product-like Riemannian manifolds are obtained. Some examples of tangential hypersurfaces are presented. Some…

Differential Geometry · Mathematics 2022-12-08 Esra Erkan , Kazuhiko Takano , Mehmet Gulbahar

Inhomogeneous Nelson's diffusion in flat spacetime with a tensor of diffusion can be described as a homogeneous one in a Riemannian manifold with this tensor of diffusion as a metric tensor. The influence of matter to the energy density of…

General Relativity and Quantum Cosmology · Physics 2012-10-09 Zahid Zakir

Lagrangian submanifolds of a Kaehler manifold are called Hamiltonian-stationary (or $H$-stationary for short) if it is a critical point of the area functional restricted to compactly supported Hamiltonian variations. In [B. Y. Chen, F.…

Analysis of PDEs · Mathematics 2013-07-16 Bang-Yen Chen

We show that for any weakly reflective submanifold of a compact isotropy irreducible Riemannian homogeneous space its inverse image under the parallel transport map is an infinite dimensional weakly reflective PF submanifold of a Hilbert…

Differential Geometry · Mathematics 2020-03-11 Masahiro Morimoto

We classify solutions of the vacuum weighted Einstein field equations on smooth metric measure spacetimes $(M,g,h\, dvol_g)$ of dimension 4, where the underlying manifold $(M,g)$ is a $pr$-wave. We use this result to provide examples of…

Differential Geometry · Mathematics 2024-07-16 Miguel Brozos-Vázquez , Diego Mojón-Álvarez

We deal with a notion of weak binormal and weak principal normal for non-smooth curves of the Euclidean space with finite total curvature and total absolute torsion. By means of piecewise linear methods, we first introduce the analogous…

Differential Geometry · Mathematics 2020-05-19 Domenico Mucci , Alberto Saracco

Let $M^n$ be either a simply connected space form or a rank-one symmetric space of noncompact type. We consider Weingarten hypersurfaces of $M\times\mathbb R$, which are those whose principal curvatures $k_1,\dots ,k_n$ and angle function…

Differential Geometry · Mathematics 2022-12-09 Ronaldo F. de Lima , Álvaro K. Ramos , João P. dos Santos