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We consider strict and complete nearly Kaehler manifolds with the canonical Hermitian connection. The holonomy representation of the canonical Hermitian connection is studied. We show that a strict and complete nearly Kaehler is locally a…

Differential Geometry · Mathematics 2007-05-23 Paul-Andi Nagy

If $\mathcal{M}=(M,\nabla)$ is an affine surface, let $\mathcal{Q}(\mathcal{M}):=\ker(\mathcal{H}+\frac1{m-1}\rho_s)$ be the space of solutions to the quasi-Einstein equation for the crucial eigenvalue. Let…

Differential Geometry · Mathematics 2018-06-19 P. Gilkey , X. Valle-Regueiro

We study semi-Riemannian submanifolds of arbitrary codimension in a Lie group $G$ equipped with a bi-invariant metric. In particular, we show that, if the normal bundle of $M \subset G$ is closed under the Lie bracket, then any normal…

Differential Geometry · Mathematics 2023-09-26 Margarida Camarinha , Matteo Raffaelli

We introduce a new notion of a periodic pencil of flat connections on a smooth algebraic variety $X$. This is a family $\nabla(s_1,...,s_n)$ of flat connections on a trivial vector bundle on $X$ depending linearly on parameters…

Algebraic Geometry · Mathematics 2024-05-07 Pavel Etingof , Alexander Varchenko

Let $\overline{M}$ be a smooth manifold with boundary $\partial M$ and interior $M$. Consider an affine connection $\nabla$ on $M$ for which the boundary is at infinity. Then $\nabla$ is projectively compact of order $\alpha$ if the…

Differential Geometry · Mathematics 2016-11-08 Andreas Cap , A. Rod Gover

For a compact connected Lie group $G$ we study the class of bi-invariant affine connections whose geodesics through $e\in G$ are the 1-parameter subgroups. We show that the bi-invariant affine connections which induce derivations on the…

Differential Geometry · Mathematics 2015-10-28 Ioannis Chrysikos

In this paper, we classify three-dimensional Lorentzian Lie groups on which Ricci tensors associated to Bott connections, canonical connections and Kobayashi-Nomizu connections are Codazzi tensors associated to these connections. We also…

Differential Geometry · Mathematics 2021-06-08 Tong Wu , Yong Wang

In this note, we discuss symmetric brackets on skew-symmetric algebroids associated with a metric structure. Given a pseudo-Riemannian metric structure, we describe symmetric brackets induced by connections with totally skew-symmetric…

Differential Geometry · Mathematics 2020-12-21 Bogdan Balcerzak

In the first part of this note we study compact Riemannian manifolds (M,g) whose Riemannian product with R is conformally Einstein. We then consider compact 6--dimensional almost Hermitian manifolds of type W_1+W_4 in the Gray--Hervella…

Differential Geometry · Mathematics 2019-01-08 Andrei Moroianu , Liviu Ornea

We study the geometry of the canonical connection on a quasi-Kaehler manifold with Norden metric. We consider the cases when the canonical connection has Kaehler curvature tensor and parallel torsion, and derive conditions for an…

Differential Geometry · Mathematics 2011-01-24 Dimitar Mekerov

In monograph of D. E. Blair "Riemannian geometry of contact and symplectic manifolds" and in the paper of S. Zamkovoy "Canonical connections on paracontact manifolds", the curvature identities respectively for contact and paracontact metric…

Differential Geometry · Mathematics 2012-09-24 Joanna Wełyczko

The paper introduces the notion of h-normal \Gamma-linear connection \nabla on 1-jet fibre bundle J^1(T,M), and studies its local d-torsions and d-curvatures togheter with theirs Bianchi identities. Also, it presents the important…

Differential Geometry · Mathematics 2010-08-02 Mircea Neagu

This paper proves that on any tamed closed almost complex four-manifold $(M,J)$ whose dimension of $J$-anti-invariant cohomology is equal to the self-dual second Betti number minus one, there exists a new symplectic form compatible with the…

Differential Geometry · Mathematics 2019-11-27 Qiang Tan , Hongyu Wang , Jiuru Zhou , Peng Zhu

We classify locally homogeneous quasi-Sasakian manifolds in dimension five that admit a parallel spinor $\psi$ of algebraic type $F \cdot \psi = 0$ with respect to the unique connection $\nabla$ preserving the quasi-Sasakian structure and…

Differential Geometry · Mathematics 2007-05-23 Thomas Friedrich , Stefan Ivanov

In this paper we study invariant almost Hermitian geometry on generalized flag manifolds. We will focus on providing examples of K\"ahler like scalar curvature metric, that is, almost Hermitian structures $(g,J)$ satisfying $s=2s_{\rm C}$,…

Differential Geometry · Mathematics 2021-12-22 Lino Grama , Ailton R. Oliveira

It is well-known that a torsion-free linear connection on a light-like manifold $(M,g)$ compatible with the degenerate metric $g$ exists if and only if $Rad(TM)$ is a Killing distribution. In case of existence, there is an infinitude of…

Differential Geometry · Mathematics 2007-05-23 T. Dereli , S. Kocak , M. Limoncu

The space of the torsion (0,3)-tensors of the linear connections on almost contact manifolds with B-metric is decomposed in 15 orthogonal and invariant subspaces with respect to the action of the structure group. Three known connections,…

Differential Geometry · Mathematics 2014-07-29 Mancho Manev , Miroslava Ivanova

In this article, we propose the following conjecture: if the Strominger connection of a compact Hermitian manifold has constant non-zero holomorphic sectional curvature, then the Hermitian metric must be K\"ahler. The main result of this…

Differential Geometry · Mathematics 2023-02-24 Shuwen Chen , Fangyang Zheng

We study the geometric properties of a $2m$-dimensional complex manifold $\mathcal{M}$ admitting a holomorphic reduction of the frame bundle to the structure group $P \subset \mathrm{Spin}(2m,\mathbb{C})$, the stabiliser of the line spanned…

Differential Geometry · Mathematics 2016-05-03 Arman Taghavi-Chabert

Given any non-compact real simple Lie group G of inner type and even dimension, we prove the existence of an invariant complex structure J and a Hermitian balanced metric with vanishing Chern scalar curvature on G and on any compact…

Differential Geometry · Mathematics 2021-06-29 Federico Giusti , Fabio Podestà