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In this article we prove a theorem of Ohsawa-Takegoshi type on compact K\"ahler manifolds. Our arguments follow the "standard" approach for this kind of extension results; however, there are many complications arising from the…

Algebraic Geometry · Mathematics 2011-04-18 Li Yi

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

Given a complete Riemannian manifold satisfying a weighted Poincar\'{e} inequality and having a bounded below Ricci curvature, various vanishing theorems for harmonic functions and harmonic 1-forms have been published. We generalized these…

Differential Geometry · Mathematics 2025-07-11 Dinh Tien Dat , Nguyen Thac Dung , Yong Luo

We study the topology and geometry of those compact Riemannian (4n)-manifolds (M,g), n > 1, with positive scalar curvature and holonomy in Sp(n)Sp(1). Up to homothety, we show that there are only finitely many such manifolds of any…

alg-geom · Mathematics 2008-02-03 Claude LeBrun

Motivated by the work of Cappell, Deturck, Gluch and Miller, we extend the notion of cohomology of harmonic forms (of a compact manifold with boundary) to the abstract setting of Hilbert complexes. Then, we present some geometric…

Differential Geometry · Mathematics 2025-12-17 Francesco Bei , Mauro Spreafico

Suppose that there exist two K\"ahler metrics $\omega$ and $\alpha$ such that the metric contraction of $\alpha$ with respect to $\omega$ is constant, i.e. $\Lambda_{\omega} \alpha = \text{const}$. We prove that for all large enough $R>0$…

Differential Geometry · Mathematics 2019-08-22 Yoshinori Hashimoto

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

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 proved $C^{3,\alpha}$ estimate for the potential of the \ka metrics…

Differential Geometry · Mathematics 2023-11-07 Reza Seyyedali

In this article, we study quasi-Einstein manifolds with constant scalar curvature. We provide a classification of compact and noncompact (possibly with boundary) $T$-flat quasi-Einstein manifolds with constant scalar curvature, where the…

Differential Geometry · Mathematics 2025-05-27 Johnatan Costa , Ernani Ribeiro , Márcio Santos

We introduce the notion of a $\theta$-almost twisted Poisson structure on manifolds, which involves incorporating a closed $1$-form $\theta$ into twisted Poisson structures under specific conditions. We provide a characterization of this…

Differential Geometry · Mathematics 2025-09-12 Nasser Saipele Nansidi , Bertuel Tangue Ndawa , Joseph Dongho

The comparison theory for the Riccati equation satisfied by the shape operator of parallel hypersurfaces is generalized to semi-Riemannian manifolds of arbitrary index, using one-sided bounds on the Riemann tensor which in the Riemannian…

dg-ga · Mathematics 2008-02-03 L. Andersson , R. Howard

The goal of this survey is to present various results concerning the cohomology of pseudoeffective line bundles on compact K{\"a}hler manifolds, and related properties of their multiplier ideal sheaves. In case the curvature is strictly…

Complex Variables · Mathematics 2015-01-05 Jean-Pierre Demailly

The Schur's theorem of antiholomorphic type is proved for arbitrary almost Hermitian manifolds, namely: If a connected almost Hermitian manifold of dimension greater or equal to 6 is of pointwise constant antiholomorphic sectional…

Differential Geometry · Mathematics 2011-08-26 Ognian Kassabov

We are concerned in this article with a classical topic in spectral geometry dating back to McKean-Singer, Patodi and Tanno: whether or not the constancy of sectional curvature (resp. holomorphic sectional curvature) of a compact Riemannian…

Differential Geometry · Mathematics 2023-12-13 Ping Li , Xiaomei Sun , Anqiang Zhu

It is proved, that if a quasi-K\"ahler manifold $M$ of dimension greater or equal to 6 is of pointwise constant antiholomorphic sectional curvature $\nu$, then $\nu$, the scalar curvature and the $*$-scalar curvature of $M$ are constants.

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

In this paper we provide new necessary and sufficient conditions for the existence of K\"ahler-Einstein metrics on small deformations of a Fano K\"ahler-Einstein manifold. We also show that the Weil-Petersson metric can be approximated by…

Differential Geometry · Mathematics 2024-03-12 Huai-Dong Cao , Xiaofeng Sun , Shing-Tung Yau , Yingying Zhang

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

In this paper we study sectional curvature bounds for Riemannian manifolds with density from the perspective of a weighted torsion free connection introduced recently by the last two authors. We develop two new tools for studying weighted…

Differential Geometry · Mathematics 2017-07-19 Lee Kennard , William Wylie , Dmytro Yeroshkin

The paper observes an almost Hermitian manifold as an example of a generalized Riemannian manifold and examines the application of a quarter-symmetric connection on the almost Hermitian manifold. The almost Hermitian manifold with…

Differential Geometry · Mathematics 2024-01-15 Milan Zlatanović , Miroslav Maksimović

For compact K\"ahlerian manifolds, the holomorphic pseudosymmetry reduces to the local symmetry if additionally the scalar curvature is constant and the structure function is non-negative. Similarly, the holomorphic Ricci-pseudosymmetry…

Differential Geometry · Mathematics 2010-11-18 Zbigniew Olszak
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