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In this paper we study sectional curvature bounds for Riemannian manifolds with density from the perspective of a weighted torsion free connection introduced recently by the last two authors. We develop two new tools for studying weighted…

Differential Geometry · Mathematics 2017-07-19 Lee Kennard , William Wylie , Dmytro Yeroshkin

In this paper, we prove a rigidity theorem for Poincar\'e-Einstein manifolds whose conformal infinity is a flat Euclidean space. The proof relies on analyzing the propagation of curvature tensors over the level sets of an adapted boundary…

Differential Geometry · Mathematics 2025-03-11 Sanghoon Lee , Fang Wang

We show an analogue of the Lorentzian splitting theorem for weighted Lorentz-Finsler manifolds: If a weighted Berwald spacetime of nonnegative weighted Ricci curvature satisfies certain completeness and metrizability conditions and includes…

Differential Geometry · Mathematics 2023-02-27 Yufeng Lu , Ettore Minguzzi , Shin-ichi Ohta

We define reduction of locally conformal Kaehler manifolds, considered as conformal Hermitian manifolds, and we show its equivalence with an unpublished construction given by Biquard and Gauduchon. We show the compatibility between this…

Differential Geometry · Mathematics 2007-05-23 Rosa Gini , Liviu Ornea , Maurizio Parton

Munteanu defined the canonical connection associated to a strongly pseudoconvex complex Finsler manifold $(M,F)$. We first prove that the holomorphic sectional curvature tensors of the canonical connection coincide with those of the…

Differential Geometry · Mathematics 2024-03-12 Hongjun Li , Hongchuan Xia

The author has elsewhere given a complete classification of those compact oriented Einstein 4-manifolds on which the self-dual Weyl curvature is everywhere positive in the direction of some self-dual harmonic 2-form. In this article,…

Differential Geometry · Mathematics 2019-03-26 Claude LeBrun

We use certain Morse functions to construct conformal metrics such that the eigenvalue vector of modified Schouten tensor belongs to a given cone. As a result, we prove that any Riemannian metric on compact 3-manifolds with boundary is…

Differential Geometry · Mathematics 2023-08-14 Rirong Yuan

On the product of two Finsler manifolds M1 M2, we consider the twisted metric F which is construct by using Finsler metrics F1 and F2 on the manifolds M1 and M2, respectively. We introduce horizontal and vertical distributions on twisted…

Differential Geometry · Mathematics 2013-02-15 E. Peyghan , A. Tayebi , L. Nourmohammadi Far

We construct a natural conformally invariant one-form of weight $-2k$ on any $2k$-dimensional pseudo-Riemannian manifold which is closely related to the Pfaffian of the Weyl tensor. On oriented manifolds, we also construct natural…

Differential Geometry · Mathematics 2022-03-08 Jeffrey S. Case

This is a survey article on the existence of locally conformally flat(LCF) and self-dual(SD) metrics on various basic 4-manifolds like simply-connected ones or product types

Differential Geometry · Mathematics 2014-03-18 Mustafa Kalafat

We introduce the concept of a Clifford-Weyl structure on a conformal manifold, which consists of an even Clifford structure parallel with respect to the tensor product of a metric connection on the Clifford bundle and a Weyl structure on…

Differential Geometry · Mathematics 2019-01-08 Charles Hadfield , Andrei Moroianu

Let $M^n(n\geq3)$ be an $n$-dimensional compact Riemannian manifold with harmonic curvature and positive scalar curvature. Assume that $M^n$ satisfies some integral pinching conditions. We give some rigidity theorems on compact manifolds…

Differential Geometry · Mathematics 2016-01-12 Hai-Ping Fu

Let (M,g) be a compact Riemannian manifold with boundary. This paper is concerned with the set of scalar-flat metrics which are in the conformal class of g and have the boundary as a constant mean curvature hypersurface. We prove that this…

Differential Geometry · Mathematics 2011-05-24 Sergio Almaraz

The various scalar curvatures on an almost Hermitian manifold are studied, in particular with respect to conformal variations. We show several integrability theorems, which state that two of these can only agree in the K\"ahler case. Our…

Differential Geometry · Mathematics 2017-03-07 Mehdi Lejmi , Markus Upmeier

This article studies the smoothness of conformal mappings between two Riemannian manifolds whose metric tensors have limited regularity. We show that any bi-Lipschitz conformal mapping or $1$-quasiregular mapping between two manifolds with…

Differential Geometry · Mathematics 2016-06-06 Tony Liimatainen , Mikko Salo

If an $m+2$-manifold $M$ is locally modeled on $\RR^{m+2}$ with coordinate changes lying in the subgroup $G=\RR^{m+2}\rtimes ({\rO}(m+1,1)\times \RR^+)$ of the affine group ${\rA}(m+2)$, then $M$ is said to be a \emph{Lorentzian similarity…

Geometric Topology · Mathematics 2011-10-11 Yoshinobu Kamishima

We prove that for any Riemannian metric $g$ on a closed orientable surface $\Sigma$ and any spacelike embedding $f:\Sigma \rightarrow M$ in a pseudo-Riemannian manifold $(M,h)$, the embedding $f$ can be $C^{0}$-approximated by a smooth…

Differential Geometry · Mathematics 2025-01-20 Alaa Boukholkhal

Berwald metrics are particular Finsler metrics which still have linear Berwald connections. Their complete classification is established in an earlier work, [Sz1], of this author. The main tools in these classification are the Simons-Berger…

Differential Geometry · Mathematics 2008-02-14 Z. I. Szabo

We define enlargeable length-structures on closed topological manifolds and then show that the connected sum of a closed $n$-manifold with an enlargeable Riemannian length-structure with an arbitrary closed smooth manifold carries no…

Differential Geometry · Mathematics 2021-05-28 Jialong Deng

Let (M,g) a compact Riemannian $n$-dimensional manifold with umbilic boundary. It is well know that, under certain hypothesis, in the conformal class of g there are scalar-flat metrics that have the boundary of M as a constant mean…

Differential Geometry · Mathematics 2020-09-03 Marco G. Ghimenti , Anna Maria Micheletti