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We introduce the concept of Bergman bundle attached to a hermitian manifold X, assuming the manifold X to be compact - although the results are local for a large part. The Bergman bundle is some sort of infinite dimensional very ample…

Complex Variables · Mathematics 2022-02-04 Jean-Pierre Demailly

We give a new definition of Levi-Civita connection for a noncommutative pseudo-Riemannian metric on a noncommutative manifold given by a spectral triple. We prove the existence-uniqueness result for a class of modules of one forms over a…

Quantum Algebra · Mathematics 2020-01-08 Jyotishman Bhowmick , Debashish Goswami , Sugato Mukhopadhyay

In these notes we survey basic concepts of affine geometry and their interaction with Riemannian geometry. We give a characterization of affine manifolds which has as counterpart those pseudo-Riemannian manifolds whose Levi-Civita…

Differential Geometry · Mathematics 2019-03-22 Fabricio Valencia

We formulate a conjecture relating the topology of a manifold's universal cover with the existence of metrics with positive $m$-intermediate curvature. We prove the result for manifolds of dimension $n\in\{3,4,5\}$ and for most choices of…

Differential Geometry · Mathematics 2025-03-19 Liam Mazurowski , Tongrui Wang , Xuan Yao

We discuss residue formulae that localize the first Chern class of a line bundle to the singular locus of a given holomorphic connection. As an application, we explain a proof for Brunella's conjecture about exceptional minimal sets of…

Complex Variables · Mathematics 2023-08-17 Masanori Adachi , Séverine Biard , Judith Brinkschulte

We consider manifolds endowed with metric contact pairs for which the two characteristic foliations are orthogonal. We give some properties of the curvature tensor and in particular a formula for the Ricci curvature in the direction of the…

Differential Geometry · Mathematics 2011-10-31 G. Bande , D. E. Blair , A. Hadjar

The purpose of this article is to classify the real hypersurfaces in complex space forms of dimension 2 that are both Levi-flat and minimal. The main results are as follows: When the curvature of the complex space form is nonzero, there is…

Differential Geometry · Mathematics 2007-05-23 Robert L. Bryant

We focus on the topology and dynamics of minimal sets and Levi-flats in surfaces of general type. Our method relies on the ergodic theory of Riemann surfaces laminations: we use harmonic measures and Lyapunov exponents. Our first result…

Complex Variables · Mathematics 2012-03-29 Bertrand Deroin , Christophe Dupont

We construct examples of flat fiber bundles over the Hopf surface such that the total spaces have no pseudoconvex neighborhood basis, admit a complete K\"ahler metric, or are hyperconvex but have no nonconstant holomorphic functions. For…

Complex Variables · Mathematics 2017-10-24 Fusheng Deng , John Erik Fornæss

Let $L$ be a (semi)-positive line bundle over a Kahler manifold, $X$, fibered over a complex manifold $Y$. Assuming the fibers are compact and non-singular we prove that the hermitian vector bundle $E$ over $Y$ whose fibers over points $y$…

Complex Variables · Mathematics 2012-10-30 Bo Berndtsson

We prove that a torsion-free sheaf $\mathcal F$ endowed with a singular hermitian metric with semi-positive curvature and satisfying the minimal extension property admits a direct-sum decomposition $\mathcal F \simeq \mathcal U \oplus…

Algebraic Geometry · Mathematics 2024-11-27 Luigi Lombardi , Christian Schnell

We show that a singular Hermitian metric on a holomorphic vector bundle over a Stein manifold which is negative in the sense of Griffiths (resp. Nakano) can be approximated by a sequence of smooth Hermitian metrics with the same curvature…

Complex Variables · Mathematics 2023-09-12 Fusheng Deng , Jiafu Ning , Zhiwei Wang , Xiangyu Zhou

Let M be a compact Riemannian manifold without boundary and let E be a Riemannian vector bundle over M. If $\Sigma$ denotes the sphere subbundle of E, we look for embeddings of $\Sigma$ into E admitting a prescribed mean curvatures of…

Differential Geometry · Mathematics 2016-02-02 Pascal Cherrier , Abdellah Hanani

We show that a unipotent vector bundle on a non-Kaehler compact complex manifold does not admit a flat holomorphic connection in general. We also construct examples of topologically trivial stable vector bundle on compact Gauduchon manifold…

Differential Geometry · Mathematics 2023-09-11 Indranil Biswas , Carlos Florentino

In this paper, we consider a special relative K\"ahler fibration that satisfies a homogenous Monge-Amp\`ere equation, which is called a Monge-Amp\`ere fibration. There exist two canonical types of generalized Weil-Petersson metrics on the…

Algebraic Geometry · Mathematics 2022-09-08 Xueyuan Wan , Xu Wang

We develop an intersection theory for a singular hemitian line bundle with positive curvature current on a smooth projective variety and irreducible curves on the variety. And we prove the existence of a natural rational fibration structure…

Algebraic Geometry · Mathematics 2007-05-23 Hajime Tsuji

Let $(M,g)$ be a Riemannian manifold, $L(M)$ its frame bundle. We construct new examples of Riemannian metrics on $L(M)$, which are obtained from Riemannian metrics on the tangent bundle $TM$. We compute the Levi--Civita connection and…

Differential Geometry · Mathematics 2012-05-07 Kamil Niedzialomski

Let $H \subset {\mathbb P}^n$ be a real-analytic subvariety of codimension one induced by a real-analytic curve in the Grassmannian $G(n+1,n)$. Assuming $H$ has a global defining function, we prove $H$ is Levi-flat, the closure of its…

Complex Variables · Mathematics 2015-05-14 Jiri Lebl

In this expository paper, we review a recent progress of the study of the Diederich--Fornaess index of complex domains with emphasis on the case of domains with Levi-flat boundary. It is exhibited that for any compact Levi-flat real…

Complex Variables · Mathematics 2020-11-16 Masanori Adachi

Let M be a compact Riemannian manifold without boundary and let E be a Riemannian vector bundle over M. If $\sigma$ denotes the sphere subbundle of E, we look for embeddings of $\sigma$ into E admitting a prescribed mean curvature.

Differential Geometry · Mathematics 2016-01-25 Pascal Cherrier , Abdellah Hanani