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Let $X$ be a compact K\"ahler manifold. We prove that if $X$ admits a smooth Hermitian metric $\omega$ with quasi-positive second Chern-Ricci curvature $\mathrm{Ric}^{(2)}(\omega)$, then $X$ is projective and rationally connected. In…

Differential Geometry · Mathematics 2020-06-25 Xiaokui Yang

In his recent work \cite{Y1}, X. Yang proved a conjecture raised by Yau in 1982 (\cite{Yau82}), which states that any compact K\"{a}hler manifold with positive holomorphic sectional curvature must be projective. In this note, we prove that…

Differential Geometry · Mathematics 2019-06-18 Kai Tang

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

In this work, we investigate compact K\"ahler manifolds with non-negative or quasi-positive mixed curvature coming from a linear combination of the Ricci and holomorphic sectional curvature, which covers various notions of curvature…

Differential Geometry · Mathematics 2024-08-27 Jianchun Chu , Man-Chun Lee , Jintian Zhu

In this paper, we study MRC fibrations of compact K\"ahler manifolds with partially semi-positive curvature. We first prove that a compact K\"ahler manifold is rationally connected if its tangent bundle is BC-$p$ positive for all $1\leq…

Differential Geometry · Mathematics 2026-03-09 Shiyu Zhang , Xi Zhang

In this paper, we first prove that a compact K\"ahler manifold is projective if it satisfies certain quasi-positive curvature conditions, including quasi-positive $S_2^\perp,\, S_2^+,\,\mbox{Ric}_3^\perp, \,\mbox{Ric}_3^+$ or…

Differential Geometry · Mathematics 2024-11-08 Yiyang Du , Yanyan Niu

In a previous paper, we proved that a projective K\"ahler manifold of positive total scalar curvature is uniruled. At the other end of the spectrum, it is a well-known theorem of Campana and Koll\'ar-Miyaoka-Mori that a projective K\"ahler…

Algebraic Geometry · Mathematics 2015-09-08 Gordon Heier , Bun Wong

In this paper, we consider {\em mixed curvature} $\mathcal{C}_{\alpha,\beta}$ for Hermitian manifolds, which is a convex combination of the first Chern Ricci curvature and holomorphic sectional curvature introduced by Chu-Lee-Tam…

Differential Geometry · Mathematics 2025-01-08 Kai Tang

In this paper, we prove that if a compact K\"ahler manifold $X$ has a smooth Hermitian metric $\omega$ such that $(T_X,\omega)$ is uniformly RC-positive, then $X$ is projective and rationally connected. Conversely, we show that, if a…

Algebraic Geometry · Mathematics 2020-11-18 Xiaokui Yang

A vanishing theorem for uniformly RC $k$-positive Hermitian holomorphic vector bundles is established. It turns out that the holomorphic tangent bundle of a compact complex manifold equipped with a positive $k$-Ricci curvature K\"{a}hler…

Differential Geometry · Mathematics 2025-09-23 Ping Li

We record two remarks. First, for a compact K\"ahler manifold with semi-positive holomorphic sectional curvature, the rational dimension of the MRC fibration is exactly the number of non-truly-flat directions. Second, for compact K\"ahler…

Differential Geometry · Mathematics 2026-05-29 Shiyu Zhang

For complete complex connections on almost complex manifolds we introduce a natural definition of compactification. This is based on almost c--projective geometry, which is the almost complex analogue of projective differential geometry.…

Differential Geometry · Mathematics 2019-10-31 Andreas Cap , A. Rod Gover

We introduce the weighted orthogonal Ricci curvature -- a two-parameter version of Ni--Zheng's orthogonal Ricci curvature. This curvature serves as a very natural object in the study of the relationship between the Ricci curvature(s) and…

Differential Geometry · Mathematics 2021-11-02 Kyle Broder , Kai Tang

In a recent work, Kai Tang conjectured that any compact Hermitian manifold with non-zero constant mixed curvature must be K\"ahler. He confirmed the conjecture in complex dimension $2$ and for Chern K\"ahler-like manifolds in general…

Differential Geometry · Mathematics 2025-10-14 Shuwen Chen , Fangyang Zheng

A recent theorem of Diverio--Trapani and Wu--Yau asserts that a compact K\"ahler manifold with a K\"ahler metric of quasi-negative holomorphic sectional curvature is projective and canonically polarized. This confirms a long-standing…

Differential Geometry · Mathematics 2023-05-04 Kyle Broder , Kai Tang

In this paper, we show that if the holomorphic tangent bundle $TX$ of a compact K\"ahler manifold $X$ is uniformly weakly RC-positive, then $X$ is projective and rationally connected. This result is previously established by Xiaokui Yang…

Differential Geometry · Mathematics 2026-04-08 Kuang-Ru Wu

Let $(M,\omega)$ be a compact K\"ahler manifold with negative holomorphic sectional curvature. It was proved by Wu-Yau and Tosatti-Yang that $M$ is necessarily projective and has ample canonical bundle. In this paper, we show that any…

Differential Geometry · Mathematics 2018-08-20 Henri Guenancia

In this paper, we introduce a concept of RC-positivity for Hermitian holomorphic vector bundles and prove that, if $E$ is an RC-positive vector bundle over a compact complex manifold $X$, then for any vector bundle $A$, there exists a…

Algebraic Geometry · Mathematics 2018-08-21 Xiaokui Yang

It is shown that a compact $n$-dimensional K\"ahler manifold with $\frac{n}{2}$-positive Calabi curvature operator has the rational cohomology of complex projective space. For even $n,$ this is sharp in the sense that the complex quadric…

Differential Geometry · Mathematics 2025-05-07 Kyle Broder , Jan Nienhaus , Peter Petersen , James Stanfield , Matthias Wink

First we confirm a conjecture asserting that any compact K\"ahler manifold $N$ with $\Ric^\perp>0$ must be simply-connected by applying a new viscosity consideration to Whitney's comass of $(p, 0)$-forms. Secondly we prove the projectivity…

Differential Geometry · Mathematics 2020-09-23 Lei Ni
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