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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

In this paper, we establish a K\"ahlerian or projectivity criterion for a class of compact Hermitian surfaces with non-positive second Chern-Ricci curvature.

Differential Geometry · Mathematics 2024-07-09 Xiaokui Yang

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 an analogue of the Donaldson-Uhlenbeck-Yau theorem for asymptotically cylindrical K\"ahler manifolds: If $\mathscr{E}$ is a reflexive sheaf over an ACyl K\"ahler manifold, which is asymptotic to a $\mu$-stable holomorphic vector…

Differential Geometry · Mathematics 2021-03-16 Adam Jacob , Thomas Walpuski

A Hermitian-symplectic metric is a Hermitian metric whose K\"ahler form is given by the $(1,1)$-part of a closed $2$-form. Streets-Tian Conjecture states that a compact complex manifold admitting a Hermitian-symplectic metric must be…

Differential Geometry · Mathematics 2025-04-07 Yuqin Guo , Fangyang Zheng

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 complete the classification of compact Hermitian manifolds admitting a flat Gauduchon connection. In particular, we establish a conjecture of Yang and Zheng, showing that apart from the cases of a flat Chern or Bismut connection, such…

Differential Geometry · Mathematics 2022-07-20 Ramiro A. Lafuente , James Stanfield

We show that a Hermitian algebraic curvature model satisfies the Gray identity if and only if it is geometrically realizable by a Hermitian manifold. Furthermore, such a curvature model can in fact be realized by a Hermitian manifold of…

Differential Geometry · Mathematics 2008-12-16 M. Brozos-Vazquez , P. Gilkey , H. Kang , S. Nikcevic

Kodaira embedding theorem provides an effective characterization of projectivity of a K\"ahler manifold in terms the second cohomology. Recently X. Yang [21] proved that any compact K\"ahler manifold with positive holomorphic sectional…

Differential Geometry · Mathematics 2023-02-24 Lei Ni , Fangyang Zheng

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

In this paper, by introducing a notion of local quasi holomorphic frame, we obtain a curvature formula for almost Hermitian manifolds which is similar to that of Hermitian manifolds. Moreover, as applications of the curvature formula, we…

Differential Geometry · Mathematics 2012-09-25 Chengjie Yu

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

For a compact K\"{a}hler-Einstein manifold $M$ of dimension $n\ge 2$, we explicitly write the expression $-c_1^n(M)+\frac{2(n+1)}{n}c_2(M)c_1^{n-2}(M)$ in the form of certain integral on the holomorphic sectional curvature and its average…

Differential Geometry · Mathematics 2025-03-25 Rong Du

We derive a canonical symmetry reduction associated to a compact non-K\"ahler Bismut-Hermitian-Einstein manifold. In real dimension $6$, the transverse geometry is conformally K\"ahler, and we give a complete description in terms of a…

Differential Geometry · Mathematics 2026-01-13 Vestislav Apostolov , Giuseppe Barbaro , Kuan-Hui Lee , Jeffrey Streets

In this paper, we derive a new monotonicity formula for the plurisuhbarmonic functions on complete K\"ahler manifolds with nonnegative bisectional curvature. As applications we derive the sharp estimates for the dimension of the spaces of…

Differential Geometry · Mathematics 2007-05-23 Lei Ni

A notable example due to Heier, Lu, Wong, and Zheng shows that there exist compact complex K\"ahler manifolds with ample canonical line bundle such that the holomorphic sectional curvature is negative semi-definite and vanishes along…

Differential Geometry · Mathematics 2023-11-21 Yongchang Chen , Gordon Heier

We prove that a compact Hermitian manifold with semi-positive but not identically zero holomorphic sectional curvature has Kodaira dimension $-\infty$. As applications, we show that Kodaira surfaces and hyperelliptic surfaces can not admit…

Differential Geometry · Mathematics 2016-04-14 Xiaokui Yang

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

This paper mainly focuses on the CR analogue of the three-circle theorem in a complete noncompact pseudohermitian manifold of vanishing torsion being odd dimensional counterpart of K\"ahler geometry. In this paper, we show that the CR…

Differential Geometry · Mathematics 2018-01-31 Shu-Cheng Chang , Yingbo Han , Chien Lin

It is well-known that the classical Schwarz lemma yields an explicit comparison of two Hermitian metrics with uniform constant negative curvature bounds through holomorphic maps between complex manifolds. In this paper, we establish Schwarz…

Differential Geometry · Mathematics 2024-12-05 Zhiyao Xiong , Xiaokui Yang , Shing-Tung Yau