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Given any integer $n\geq 2$, we construct a compact K\"ahler-Einstein manifold of dimension n of negative sectional curvature which is not covered by the ball.

Differential Geometry · Mathematics 2026-05-05 Henri Guenancia , Ursula Hamenstädt

In this article we continue the study of the two curvature notions for K\"ahler manifolds introduced by the first named author earlier: the so-called cross quadratic bisectional curvature (CQB) and its dual ($^d$CQB). We first show that…

Differential Geometry · Mathematics 2025-03-18 Lei Ni , Fangyang Zheng

We show that a compact quaternionic-K\"ahler manifold with positive scalar curvature and nonnegative sectional curvature is isometric to a symmetric space. This extends a classical theorem of Berger.

Differential Geometry · Mathematics 2025-06-30 S. Brendle , U. Semmelmann

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 show that any compact K$\"a$hler manifold homotopic to a compact Riemannian manifold with negative sectional curvature admits a K$\"a$hler-Einstein metric of general type. Moreover, we prove that, on a compact symplectic…

Differential Geometry · Mathematics 2017-11-10 Bing-Long Chen , Xiaokui Yang

In this article we give necessary and sufficient conditions for an irreducible K\"ahler C-space with $b_2=1$ to have nonnegative or positive quadratic bisectional curvature, assuming the space is not Hermitian symmetric. In the cases of the…

Differential Geometry · Mathematics 2012-12-21 Albert Chau , Luen-Fai Tam

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

For a compact relative K\"ahler fibration over a compact K\"ahler manifold with negative holomorphic sectional curvature, if the relative K\"ahler form on each fiber also exhibits negative holomorphic sectional curvature, we can construct…

Differential Geometry · Mathematics 2026-01-16 Xueyuan Wan

Let $(M^n, g)$ be a compact K\"ahler manifold with nonpositive bisectional curvature. We show that a finite cover is biholomorphic and isometric to a flat torus bundle over a compact K\"ahler manifold $N^k$ with $c_1 < 0$. This confirms a…

Differential Geometry · Mathematics 2014-04-30 Gang Liu

In this paper, we establish a "pseudo-effective" version of the holonomy principle for compact K\"{a}hler manifolds with nonnegative holomorphic sectional curvature. As applications, we prove that if a compact complex manifold $M$ admits a…

Differential Geometry · Mathematics 2024-08-07 Shiyu Zhang , Xi Zhang

We show that if $M = X \times Y$ is the product of two complex manifolds (of positive dimensions), then $M$ does not admit any complete K\"ahler metric with bisectional curvature bounded between two negative constants. More generally, a…

Differential Geometry · Mathematics 2008-01-03 Harish Seshadri , Fangyang Zheng

In this article we study compact K\ahler manifolds satisfying a certain nonnegativity condition on the bisectional curvature. Under this condition, we show that the scalar curvature is nonnegative and that the first Chern class is positive…

Differential Geometry · Mathematics 2011-09-01 Albert Chau , Luen-Fai Tam

We give a mathematical exposition of the Page metric, and introduce an efficient coordinate system for it. We carefully examine the submanifolds of the underlying smooth manifold, and show that the Page metric does not have positive…

Differential Geometry · Mathematics 2019-04-11 Mustafa Kalafat , Caner Koca

We construct a simply connected compact manifold which has complex and symplectic structures but does not admit K\"ahler metrics, in the lowest possible dimension where this can happen, that is, dimension 6. Such a manifold is automatically…

Symplectic Geometry · Mathematics 2014-11-17 Giovanni Bazzoni , Marisa Fernández , Vicente Muñoz

Let (M,J) be a compact complex 2-manifold which which admits a Kaehler metric for which the integral of the scalar curvature is non-negative. Also suppose that M does not admit a Ricci-flat K\"ahler metric. Then if M is blown up at…

dg-ga · Mathematics 2008-02-03 Jongsu Kim , Claude LeBrun , Massimiliano Pontecorvo

Let $M=X\times Y$ be the product of two complex manifolds of positive dimensions. In this paper, we prove that there is no complete K\"ahler metric $g$ on $M$ such that: either (i) the holomorphic bisectional curvature of $g$ is bounded by…

Differential Geometry · Mathematics 2009-09-30 Luen-Fai Tam , Chengjie Yu

Motivated by the recent work of Wu and Yau on the ampleness of canonical line bundle for compact K\"ahler manifolds with negative holomorphic sectional curvature, we introduce a new curvature notion called $\textbf{real bisectional…

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

We classify compact almost-K\"ahler four manifolds with nonnegative biorthogonal curvature.

Differential Geometry · Mathematics 2023-11-29 Inyoung Kim

We prove the formality and the evenness of odd-degree Betti numbers for compact K\"ahler orbifolds, by adapting the classical proofs for K\"ahler manifolds. As a consequence, we obtain examples of symplectic orbifolds not admitting any…

Differential Geometry · Mathematics 2016-12-30 Giovanni Bazzoni , Indranil Biswas , Marisa Fernández , Vicente Muñoz , Aleksy Tralle

In this short note, using Siu-Yau's method [14], we give a new proof that any n-dimensional compact Kahler manifold with positive orthogonal bisectional curvature must be biholomorphic to $\mathbb{P}^n$.

Differential Geometry · Mathematics 2017-10-30 Huitao Feng , Kefeng Liu , Xueyuan Wan
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