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Related papers: A note on the almost one half holomorphic pinching

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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

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

Let $X$ be a compact K{\"a}hler manifold of dimension three. We prove that there exists a projective manifold $Y$ such that $\pi\_1(X)\simeq \pi\_1(Y)$. We also prove the bimeromorphic existence of algebraic approximations for compact…

Algebraic Geometry · Mathematics 2020-01-08 Benoît Claudon , Andreas Höring , Hsueh-Yung Lin

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

We consider a compact K\"ahler manifold admitting a constant scalar curvature K\"ahler metric and with no nontrivial holomorphic vector fields. After blowing up the manifold at finitely many points, we prove the existence of constant scalar…

Differential Geometry · Mathematics 2026-05-28 Yueqing Feng

Criterions for constancy of the holomorphic sectional curvature and the antiholomorphic sectional curvature are proved for almost Hermitian manifolds. It is shown, that an almost Hermitian manifold satisfying the axiom of antiholomorphic…

Differential Geometry · Mathematics 2010-04-22 Ognian Kassabov

We show that a compact oriented riemannian four-manifold with harmonic and pinched self-dual Weyl curvature is anti-self-dual if the type is nonpositive. The main part is to show that there is an almost-K\"ahler structure outside the zero…

Differential Geometry · Mathematics 2025-12-02 Inyoung Kim

Sectional curvature bounds are of central importance in the study of Riemannian manifolds, both in smooth differential geometry and in the generalized synthetic setting of Alexandrov spaces. Riemannian metrics along with metric spaces of…

Differential Geometry · Mathematics 2026-01-30 Darius Erös , Michael Kunzinger , Argam Ohanyan , Alessio Vardabasso

In recent papers Wu-Yau, Tosatti-Yang and Diverio-Trapani, used some natural differential inequalities for compact K\"ahler manifolds with quasi negative holomorphic sectional curvature to derive positivity of the canonical bundle. In this…

Differential Geometry · Mathematics 2018-01-09 Stefano Trapani

In their seminal work (\cite{CC}, \cite{CC2}), Chen and Cheng proved apriori estimates for the constant scalar curvature metrics on compact K\"ahler manifolds. They also prove $C^{3,\alpha}$-estimate for the potential of the K\"ahler…

Differential Geometry · Mathematics 2023-11-03 Zhiqin Lu , Reza Seyyedali

The main result of this note is that, for each $n\in \{1,2,3,\ldots\}$, there exists a Hodge metric on the $n$-th Hirzebruch surface whose positive holomorphic sectional curvature is $\frac{1}{(1+2n)^2}$-pinched. The type of metric under…

Differential Geometry · Mathematics 2015-07-24 Angelynn Alvarez , Ananya Chaturvedi , Gordon Heier

We use an index-theoretic technique of Hitchin to show that the space of complete Riemannian metrics of nonnegative sectional curvature on certain open spin manifolds has nontrivial homotopy groups in infinitely many degrees. A new…

Differential Geometry · Mathematics 2018-05-08 Igor Belegradek

A long-standing conjecture in non-K\"ahler geometry states that if the Chern (or Levi-Civita) holomorphic sectional curvature of a compact Hermitian manifold is a constant $c$, then the metric must be K\"ahler when $c\neq 0$ and must be…

Differential Geometry · Mathematics 2026-03-17 Yulu Li , Fangyang Zheng

By solving the Cauchy problem for the Hodge-Laplace heat equation for $d$-closed, positive $(1, 1)$-forms, we prove an optimal gap theorem for K\"ahler manifolds with nonnegative bisectional curvature which asserts that the manifold is flat…

Differential Geometry · Mathematics 2015-05-27 Lei Ni

Based on Nijenhuis-Richardson bracket and bidegree on the cohomology complex for a Lie conformal algebra, we develop a twisting theory of Lie conformal algebras. By using derived bracket constructions, we construct $L_\infty$-algebras from…

Quantum Algebra · Mathematics 2023-08-16 Lamei Yuan , Jiefeng Liu

Let M be a complete Riemannian manifold, D a Dirac-type operator on M whose Weitzenbock curvature is uniformly positive on the complement of a subset Z of M. We show that the coarse index of D is localized to the K-theory of the coarse…

K-Theory and Homology · Mathematics 2012-11-05 John Roe

We derive some consequences of the Liouville theorem for plurisubharmonic functions of L.-F. Tam and the author. The first result provides a nonlinear version of the complex splitting theorem (which splits off a factor of $\mathbb{C}$…

Differential Geometry · Mathematics 2018-08-28 Lei Ni

A general theory of partial balayage on Riemannian manifolds is developed, with emphasis on compact manifolds. Partial balayage is an operation of sweeping measures, or charge distributions, to a prescribed density, and it is closely…

Differential Geometry · Mathematics 2016-05-11 Björn Gustafsson , Joakim Roos

The main point of this paper is that, under suitable conditions on the mean curvature and the Ricci curvature of the ambient space, we can extend Choi-Schoen's Compactness Theorem to compact embedded minimal surfaces to simple immersed…

Differential Geometry · Mathematics 2011-08-30 Jose M. Espinar

Inspired by the problem of classifying Einstein manifolds with positive scalar curvature, we prove that an Einstein four-manifold whose associated twistor space has scalar curvature constant on the fibers of the twistor bundle is half…

Differential Geometry · Mathematics 2025-07-23 Davide Dameno