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We study the affine quasi-Einstein equation, a second order linear homogeneous equation, which is invariantly defined on any affine manifold. We prove that the space of solutions is finite-dimensional, and its dimension is a strongly…

Differential Geometry · Mathematics 2017-05-24 Miguel Brozos Vázquez , Eduardo García Río , Peter Gilkey , Xabier Valle Regueiro

We construct the Einstein equation for an invariant Riemannian metric on the exceptional full flag manifold $M=G_2/T$. By computing a Gr\"obner basis for a system of polynomials of multi-variables we prove that this manifold admits exactly…

Differential Geometry · Mathematics 2015-11-26 Andreas Arvanitoyeorgos , Ioannis Chrysikos , Yusuke Sakane

In this paper, we classify $n$-dimensional ($n\geq 5$) quasi-Einstein manifolds with harmonic Weyl curvature, thus extending the work of Shin \cite{Shin} in dimension four for quasi-Einstein manifolds and refining the work of…

Differential Geometry · Mathematics 2025-12-01 Huai-Dong Cao , Fengjiang Li , James Siene

Minimal surfaces and Einstein manifolds are among the most natural structures in differential geometry. Whilst minimal surfaces are well understood, Einstein manifolds remain far less so. This exposition synthesises together a set of…

Differential Geometry · Mathematics 2025-08-19 Mia Beard

The harmonicity condition of the curvature 2-form of a pseudo- Riemannian manifold is formulated on the basis of annulment of this form by the de Rham-Lichnerowicz Laplacian. The following theorem is proved: The curvature 2-form of any…

General Relativity and Quantum Cosmology · Physics 2007-05-23 O. V. Babourova , B. N. Frolov

We give a condition for an almost constant-type manifold to be a constant-type manifold, and holomorphic and $R$-invariant submanifolds of almost Hermitian manifolds are studied. Generalizations of some results in [5] are given.

Differential Geometry · Mathematics 2013-11-12 Hakan Mete Taştan

By a theorem of Kirchhoff if the six sphere admits an almost complex structure then the seven sphere is parallelizable, more crucial, he exhibited an explicit global frame constructed out of the given almost complex structure. This result…

Differential Geometry · Mathematics 2018-04-17 Lázaro O. Rodríguez Díaz

We obtain a class of locally symmetric Kaehler Einstein structures on the cotangent bundle of a Riemannian manifold of negative sectional curvature. Similar results are obtained in the case of a Riemannian manifold of positive sectional…

Differential Geometry · Mathematics 2007-05-23 D. D. Porosniuc

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,

We compute almost-complex invariants $h^{p,0}_{\overline\partial}$, $h^{p,0}_{\text{Dol}}$ and almost-Hermitian invariants $h^{p,0}_{\bar\delta}$ on families of almost-K\"ahler and almost-Hermitian $6$-dimensional solvmanifolds. Finally, as…

Differential Geometry · Mathematics 2021-09-21 Nicoletta Tardini , Adriano Tomassini

We formulate the deformation theory for instantons on nearly K\"ahler six-manifolds using spinors and Dirac operators. Using this framework we identify the space of deformations of an irreducible instanton with semisimple structure group…

Differential Geometry · Mathematics 2016-06-29 Benoit Charbonneau , Derek Harland

We study nearly-Kahler 6-manifolds equipped with a cohomogeneity-two Lie group action for which the principal orbits are coisotropic. If the metric is complete, then we show that this last condition is automatically satisfied, and both the…

Differential Geometry · Mathematics 2018-10-31 Jesse Madnick

In joint work with Chen and Weber, the author has elsewhere shown that CP2#2(-CP2) admits an Einstein metric. The present paper gives a new and rather different proof of this fact. Our results include new existence theorems for extremal…

Differential Geometry · Mathematics 2010-10-05 Claude LeBrun

We prove that any totally geodesic hypersurface $N^5$ of a 6-dimensional nearly K\"ahler manifold $M^6$ is a Sasaki-Einstein manifold, and so it has a hypo structure in the sense of \cite{ConS}. We show that any Sasaki-Einstein 5-manifold…

Differential Geometry · Mathematics 2014-02-26 Marisa Fernández , Stefan Ivanov , Vicente Muñoz , Luis Ugarte

It is proved that a compact Kahler manifold whose Ricci tensor has two distinct, constant, non-negative eigenvalues is locally the product of two Kahler-Einstein manifolds. A stronger result is established for the case of Kahler surfaces.…

Differential Geometry · Mathematics 2019-01-08 Vestislav Apostolov , Tedi Draghici , Andrei Moroianu

We show the existence of strictly almost-Kahler anti-self-dual metrics on certain 4-manifolds by deforming scalar-flat Kahler metrics. On the other hand, we prove the non-existence of such metrics on certain other 4-manifolds by means of…

Differential Geometry · Mathematics 2015-11-25 Inyoung Kim

We show that a para-quaternion nearly Kahler manifold is necessarily a para-quaternion Kahler manifold

Differential Geometry · Mathematics 2007-05-23 A. M. Ionescu , G. E. Vilcu

In this expository article we review the problem of finding Einstein metrics on compact K\"ahler manifolds and Sasaki manifolds. In the former half of this article we see that, in the K\"ahler case, the problem fits better with the notion…

Differential Geometry · Mathematics 2008-11-09 Akito Futaki , Hajime Ono

We give four constructions of non-$\partial\bar\partial$ (hence non-K\"ahler) manifolds: (1) A simply connected page-$1$-$\partial\bar\partial$-manifold (2) A simply connected $dd^c+3$-manifold (3) For any $r\geq 2$, a simply connected…

Algebraic Geometry · Mathematics 2023-06-27 Hisashi Kasuya , Jonas Stelzig

In this study, we present a new analogue of Euler-Lagrange and Hamilton equations on an almost K\"ahler model of a Finsler manifold. Also, we give some corollories about the related mechanical systems and equations.

Mathematical Physics · Physics 2012-11-08 Mehmet Tekkoyun , Oğuzhan Çelik