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It is proved that if an AK2-manifold of dimension greater or equal to 6 is of pointwise constant antiholomorphic sectional curvature, then it is a 6-dimensional manifold of constant negative sectional curvature or a K\"ahler manifold of…

Differential Geometry · Mathematics 2010-09-15 Ognian Kassabov

We consider closed manifolds that admit a metric locally isometric to a product of symmetric planes. For such manifolds, we prove that the Euler characteristic is an obstruction to the existence of flat structures, confirming an old…

Geometric Topology · Mathematics 2009-05-23 Michelle Bucher , Tsachik Gelander

In this paper, we investigate the problem of prescribing Chern scalar curvatures on complete noncompact Hermitian manifolds with nonpositive curvatures, and establish some existence results. In particular, we obtain some sufficient…

Differential Geometry · Mathematics 2026-01-29 Weike Yu

We consider the conjecture of Chen and Nie concerning the space forms for canonical metric connections of compact Hermitian manifolds. We verify the conjecture for two special types of Hermitian manifolds: complex nilmanifolds with…

Differential Geometry · Mathematics 2025-04-07 Shuwen Chen , Fangyang Zheng

Motivated by a recent work of Chen-Zheng [8] on Strominger space forms, we prove that a compact Hermitian surface with pointwise constant holomorphic sectional curvature with respect to a Gauduchon connection $\nabla^t $ is either K\"ahler,…

Differential Geometry · Mathematics 2022-02-15 Haojie Chen , Xiaolan Nie

A Hermitian metric on a complex manifold of complex dimension $n$ is called {\em astheno-K\"ahler} if its fundamental $2$-form $F$ satisfies the condition $\partial \overline \partial F^{n - 2} =0$. If $n =3$, then the metric is {\em strong…

Differential Geometry · Mathematics 2014-02-26 Anna Fino , Adriano Tomassini

In this paper, we consider general $k$th-mixed curvature $\mathcal{C}^{(k)}_{\alpha,\beta}$ ($\beta\neq0$) for Hermitian manifolds, which is a convex combination of the $k$th Chern Ricci curvature and holomorphic sectional curvature. We…

Differential Geometry · Mathematics 2025-10-13 Weiguo Chen , Kai Tang

We show that if a compact complex manifold admits a K\"ahler metric whose holomorphic sectional curvature is everywhere non positive and strictly negative in at least one point, then its canonical bundle is positive.

Differential Geometry · Mathematics 2018-07-19 Simone Diverio , Stefano Trapani

In this paper we study almost complex manifolds admitting a quasi-K\"ahler Chern-flat metric (Chern-flat means that the holonomy of the Chern connection is trivial). We prove that in the compact case such manifolds are all nilmanifolds.…

Differential Geometry · Mathematics 2014-05-26 Antonio J. Di Scala , Luigi Vezzoni

It is known, that if a 2m-dimensional Kahler manifold satisfies the axiom of holomorphic 2n-spheres (1<n<m) or the axiom of antiholomorphic n-spheres (2<n), it is of constant holomorphic sectional curvature. In this paper the same result is…

Differential Geometry · Mathematics 2010-04-26 Ognian Kassabov

Let H be a 4 dimensional almost Hermitian manifold which satisfies the Kaehler identity. Then H is complex Osserman if and only if H has constant holomorphic sectional curvature. We also classify in arbitrary dimensions all the complex…

Differential Geometry · Mathematics 2010-03-30 Miguel Brozos-Vazquez , Peter Gilkey

We prove that compact complex manifolds with admitting metrics with negative Chern curvature operator either admit a $dd^c$-exact positive (1,1) current, or are K\"ahler with ample canonical bundle. In the case of complex surfaces we obtain…

Differential Geometry · Mathematics 2019-04-01 Man-Chun Lee , Jeffrey Streets

On a complex manifold an Hermitian metric which is simultaneously SKT and balanced has to be necessarily K\"ahler. It has been conjectured that if a compact complex manifold (M,J) has an SKT metric and a balanced metric both compatible with…

Differential Geometry · Mathematics 2015-06-18 Anna Fino , Luigi Vezzoni

A classification theorem for nearly K\"ahler manifolds of constant antiholomorphic sectional curvature is proved.

Differential Geometry · Mathematics 2010-09-15 Georgi Ganchev , Ognian Kassabov

In this paper, we show that every harmonic map from a compact K\"ahler manifold with uniformly RC-positive curvature to a Riemannian manifold with non-positive complex sectional curvature is constant. In particular, there is no non-constant…

Differential Geometry · Mathematics 2018-09-13 Jun Wang , Xiaokui Yang

We show that every quaternion-K\"ahler manifold of negative scalar curvature is stable as an Einstein manifold and therefore scalar curvature rigid. In particular, this implies that every irreducible nonpositive Einstein manifold of special…

Differential Geometry · Mathematics 2024-12-19 Klaus Kroencke , Uwe Semmelmann

We prove the following results: An almost Hermitian manifold of indefinite metric is of pointwise constant holomorphic sectional curvature if the holomorphic sectional curvature is bounded from above and from below. If the antiholomorphic…

Differential Geometry · Mathematics 2010-08-12 Adrijan Borisov , Ognian Kassabov

We prove that any Kaehler manifold admitting a flat complex conformal connection is a Bochner-Kaehler manifold with special scalar distribution and zero geometric constants. Applying the local structural theorem for such manifolds we obtain…

Differential Geometry · Mathematics 2007-06-07 Georgi Ganchev , Vesselka Mihova

We show that, under the definiteness of holomorphic sectional curvature, the spaces of some holomorphic tensor fields on compact Chern-K\"{a}hler-like Hermitian manifolds are trivial. These can be viewed as counterparts to Bochner's…

Differential Geometry · Mathematics 2024-09-06 Ping Li

In this paper we give a partial affirmative answer to a conjecture of Greene-Wu and Yau. We prove that a complete noncompact K\"ahler surface with positive and bounded sectional curvature and with finite analytic Chern number $c_{1}(M)^{2}$…

Differential Geometry · Mathematics 2007-05-23 Bing-Long Chen , Xi-Ping Zhu