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We give a partial account of some problems concerning cohomological invariants and metric properties of complex non-K\"ahler manifolds.

Differential Geometry · Mathematics 2026-02-04 Daniele Angella , Nicoletta Tardini

We obtain a class of locally symetric Kaehler Einstein structures on the nonzero cotangent bundle of a Riemannian manifold of positive constant sectional curvature. The obtained class of Kaehler Einstein structures depends on one essential…

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

The field equations associated with the Born-Infeld-Einstein action are derived using the Palatini variational technique. In this approach the metric and connection are varied independently and the Ricci tensor is generally not symmetric.…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Dan N. Vollick

There are studied in details 5-dimensional pseudo-Riemannian manifolds equipped with the structure analogous to the almost cosymplectic (almost coKaehler) structure. The curvature by assumption commutes with the structure affinor and all…

Differential Geometry · Mathematics 2013-08-30 Piotr Dacko

The purpose of this paper is to investigate canonical metrics on a semi-stable vector bundle E over a compact Kahler manifold X. It is shown that, if E is semi-stable, then Donaldson's functional is bounded from below. This implies that E…

Differential Geometry · Mathematics 2013-08-27 Adam Jacob

We construct quasi-Einstein metrics on some hypersurface families. The hypersurfaces are circle bundles over the product of Fano, K\"ahler-Einstein manifolds. The quasi-Einstein metrics are related to various gradient K\"ahler-Ricci…

Differential Geometry · Mathematics 2015-06-04 Stuart James Hall

In this note we generalize our previous result, stating that if $(M_1,g_1)$ and $(M_2,g_2)$ are compact Riemannian manifolds, then any Einstein metric on the product $M:=M_1\times M_2$ of the form $g=e^{2f_1}g_1+e^{2f_2}g_2$, with $f_1\in…

Differential Geometry · Mathematics 2025-04-11 Andrei Moroianu , Mihaela Pilca

Representations of coherent state Lie algebras on coherent state manifolds as first order differential operators are presented. The explicit expressions of the differential action of the generators of semisimple Lie groups determine for…

Differential Geometry · Mathematics 2007-05-23 S. Berceanu , A. Gheorghe

Motivated by understanding the limiting case of a certain systolic inequality we study compact Riemannian manifolds having all harmonic 1-forms of constant length. We give complete characterizations as far as K\"ahler and hyperbolic…

Differential Geometry · Mathematics 2008-10-10 Paul-Andi Nagy

We study nonlinear gravity theories in both the metric and the Palatini (metric-affine) formalisms. The nonlinear character of the gravity lagrangian in the metric formalism causes the appearance of a scalar source of matter in Einstein's…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Gonzalo J. Olmo , William Komp

Let the warped product $M^n=L^m\times_\varphi F^{n-m}$, $n\geq m+3\geq 8$, of Riemannian manifolds be an Einstein manifold with Ricci curvature $\rho$ that admits an isometric immersion into Euclidean space with codimension two. Under the…

Differential Geometry · Mathematics 2022-10-19 M. Dajczer , C. -R. Onti , Th. Vlachos

We study metric structures on a smooth manifold (introduced in our recent works and called a weak contact metric structure and a weak K-structure) which generalize the metric contact and K-contact structures, and allow a new look at the…

Differential Geometry · Mathematics 2023-04-04 Vladimir Rovenski

We show that Hermitian metrics with vanishing holomorphic curvature on compact complex manifolds with pseudoeffective canonical bundle are conformally balanced. Pluriclosed metrics with vanishing holomorphic curvature on compact K\"ahler…

Differential Geometry · Mathematics 2024-08-06 Kyle Broder , Kai Tang

We study infinitesimal Einstein deformations on compact flat manifolds and on product manifolds. Moreover, we prove refinements of results by Koiso and Bourguignon which yield obstructions on the existence of infinitesimal Einstein…

Differential Geometry · Mathematics 2015-08-05 Klaus Kroencke

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 study the affine quasi-Einstein Equation for homogeneous surfaces. This gives rise through the modified Riemannian extension to new half conformally flat generalized quasi-Einstein neutral signature $(2,2)$ manifolds, to conformally…

Differential Geometry · Mathematics 2017-07-21 Miguel Brozos-Vázquez , Eduardo García-Río , Peter Gilkey , Xabier Valle-Regueiro

Fine and Premoselli (FP) constructed the first examples of manifolds that do not admit a locally symmetric metric but do admit a negatively curved Einstein metric. The manifolds here are hyperbolic branched covers like those used by Gromov…

Differential Geometry · Mathematics 2025-05-02 Jean-François Lafont , Barry Minemyer

Given an effectively parameterized family of canonically polarized manifolds the Kaehler-Einstein metrics on the fibers induce a hermitian metric on the relative canonical bundle. We use a global elliptic equation to show that this metric…

Complex Variables · Mathematics 2010-10-20 Georg Schumacher

Quasi-Einstein manifolds are well-studied generalizations of Einstein manifolds. This includes gradient Ricci solitons and has a natural correspondence with the warped product Einstein manifolds. A quasi-Einstein metric is said to be rigid…

Differential Geometry · Mathematics 2026-04-24 Atreyee Bhattacharya , Sayoojya Prakash

We prove that an admissible manifold (as defined by Apostolov, Calderbank, Gauduchon and T{\o}nnesen-Friedman), arising from a base with a local K\"ahler product of constant scalar curvature metrics, admits Generalized Quasi-Einstein…

Differential Geometry · Mathematics 2009-09-08 Gideon Maschler , Christina W. Tønnesen-Friedman
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