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In this paper we prove that, at least in even complex dimensions, the ratio of Chern numbers for a closed complex hyperbolic branched cover manifold are not all equal to the corresponding ratio of Chern numbers for a closed complex…

Differential Geometry · Mathematics 2025-05-26 Barry Minemyer

In this paper we construct an almost negatively $1/4$-pinched Riemannian metric on a class of compact manifolds recently discovered by Stover and Toledo in [17]. It is known that these manifolds are K\"{a}hler and not locally symmetric.…

Differential Geometry · Mathematics 2024-11-04 Barry Minemyer

We present some formulae related to the Chern-Ricci curvatures and scalar curvatures of special Hermitian metrics. We prove that a compact locally conformal K\"{a}hler manifold with constant nonpositive holomorphic sectional curvature is…

Differential Geometry · Mathematics 2019-05-09 Haojie Chen , Lingling Chen , Xiaolan Nie

This paper is the first step in a systematic project to study examples of K\"ahler manifolds with positive holomorphic sectional curvature ($H > 0$). Previously Hitchin proved that any compact K\"ahler surface with $H>0$ must be rational…

Differential Geometry · Mathematics 2023-03-31 Bo Yang , Fangyang Zheng

We establish a regularity result for the metric on any 4-dimensional extremal K\"ahler manifold, and a weak compactness theorem on the space of such metrics. Specifically, the sectional curvature at a point is bounded when the quantity…

Differential Geometry · Mathematics 2011-05-11 Brian Weber

Motivated by a previous work of Zheng and the second named author, we study pinching constants of compact K\"ahler manifolds with positive holomorphic sectional curvature. In particular we prove a gap theorem following the work of Petersen…

Differential Geometry · Mathematics 2017-09-11 Xiaodong Cao , Bo Yang

In this survey, we consider various analytic problems related to the geometry of the Chern connection on Hermitian manifolds, such as the existence of metrics with constant Chern-scalar curvature, generalizations of the K\"ahler-Einstein…

Complex Variables · Mathematics 2025-05-19 Daniele Angella

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

We prove that there exist K\"{a}hler manifolds that are not homotopy equivalent to a quotient of complex hyperbolic space but which admit a Riemannian metric with nonpositive curvature operator. This shows that K\"{a}hler manifolds do not…

Differential Geometry · Mathematics 2024-01-31 Barry Minemyer

In this paper, we establish Chern number identities on compact complex surfaces. As an application, we prove that if $(M,g)$ is a compact Riemannian four-manifold with constant scalar curvature and admits a compatible complex structure $J$…

Differential Geometry · Mathematics 2025-08-18 Xiaokui Yang

It is proved that if an almost K\"ahler manifold of dimension greater or equal to 8 is of pointwise constant antiholomorphic sectional curvature, then it is a complex space form.

Differential Geometry · Mathematics 2010-10-08 Maria Falcitelli , Angela Farinola , Ognian Kassabov

In this paper, we study closed four-dimensional manifolds. In particular, we show that under various new pinching curvature conditions (for example, the sectional curvature is no more than 5/6 of the smallest Ricci eigenvalue) then the…

Differential Geometry · Mathematics 2022-08-31 Xiaodong Cao , Hung Tran

We show that if a closed manifold of dimension at least four admits a negatively curved metric that is almost Einstein in a suitable sense, then it admits a genuine Einstein metric of negative sectional curvature. Importantly, the pinching…

Differential Geometry · Mathematics 2025-12-30 Frieder Jäckel

In \cite{CC1}, Cheeger-Colding considered manifolds with lower Ricci curvature bound and gave some almost rigidity results about warped products including almost metric cone rigidity and quantitative splitting theorem. As a generalization…

Differential Geometry · Mathematics 2022-01-21 Lina Chen

A type of almost contact hypersurfaces with Norden metric of a Kaehler manifold with Norden metric is considered. The curvature tensor and the special sectional curvatures are characterized. The canonical connection on such manifolds is…

Differential Geometry · Mathematics 2012-05-08 Mancho Manev , Marta Teofilova

We show in this article that K\"{a}hler hyperbolic manifolds satisfy a family of optimal Chern number inequalities and the equality cases can be attained by some compact ball quotients. These present restrictions to complex structures on…

Differential Geometry · Mathematics 2019-09-10 Ping Li

The Kaehler manifolds of quasi-constant holomorphic sectional curvatures are introduced as Kaehler manifolds with complex distribution of codimension two, whose holomorphic sectional curvature only depends on the corresponding point and the…

Differential Geometry · Mathematics 2008-03-04 Georgi Ganchev , Vesselka Mihova

The basic class of the non-integrable almost complex manifolds with Norden metric is considered. Its curvature properties are studied. The isotropic Kaehler type of investigated manifolds is introduced and characterized geometrically.

Differential Geometry · Mathematics 2012-05-08 Dimitar Mekerov , Mancho Manev

We show the theorem which provides some sufficient condition to the non-existence of a complete K\"ahler--Einstein metric of negative scalar curvature whose holomorphic sectional curvature is negatively pinched: Let $\Omega$ be a bounded…

Differential Geometry · Mathematics 2023-05-23 Gunhee Cho

In this paper, we investigate the Chern number inequalities on $4$-dimensional K\"ahler manifolds admitting the deformed Hermitian-Yang-Mills metrics under the assumption $\hat\theta\in (\pi,2\pi)$.

Differential Geometry · Mathematics 2020-08-18 Xiaoli Han , Xishen Jin
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