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Related papers: Projectivity criteria for K\"ahler morphisms

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Let $\pi\cln X\to \Delta^m$ be a proper smooth K\"ahler morphism from a complex manifold $X$ to the unit polydisc $\Delta^m$. Suppose the fibers over the complement of a proper analytic subset are biholomorphic to a fixed projective…

Algebraic Geometry · Mathematics 2026-05-11 Mu-Lin Li , Xiao-Lei Liu

The generalisation of the well-known (Hilbert polynomial) criterion for flatness of a projective morphism of Noetherian schemes is given for the case of nonreduced base of the morphism.

Algebraic Geometry · Mathematics 2012-09-28 Nadezda V. Timofeeva

We study the existence of canonical K\"ahler metrics on the projectivisation of strictly Mumford semistable holomorphic vector bundles over a complex curve. We also provide an algebro-geometric characterization of these metrics.

Differential Geometry · Mathematics 2017-05-17 Julien Keller

We explore the relationship between fibrations arising naturally from a surjective morphism to an abelian variety. These fibrations encode geometric information about the morphism. Our study focuses on the interplay of these fibrations and…

Algebraic Geometry · Mathematics 2024-07-24 Fanjun Meng

Two K\"ahler metrics on a complex manifold are called c-projectively equivalent if their $J$-planar curves coincide. These curves are defined by the property that the acceleration is complex proportional to the velocity. We give an explicit…

Differential Geometry · Mathematics 2015-10-02 Alexey V. Bolsinov , Vladimir S. Matveev , Stefan Rosemann

We prove that projectivity is an open condition for deformations of algebraic spaces with rational singularities. V.2: references updated and corrected.

Algebraic Geometry · Mathematics 2021-05-25 János Kollár

We study smooth foliations of arbitrary codimension on homogeneous compact K\"ahler manifolds. We prove that smooth foliations on rational compact homogeneous manifolds are locally trivial fibrations and classify the smooth foliations with…

Algebraic Geometry · Mathematics 2015-01-20 Federico Lo Bianco , Jorge Vitorio Pereira

This paper concerns the explicit construction of extremal Kaehler metrics on total spaces of projective bundles, which have been studied in many places. We present a unified approach, motivated by the theory of hamiltonian 2-forms (as…

Differential Geometry · Mathematics 2015-06-26 Vestislav Apostolov , David M. J. Calderbank , Paul Gauduchon , Christina W. Tonnesen-Friedman

On an almost complex manifold, a quasi-K\"{a}hler metric, with canonical connection in the c-projective class of a given minimal complex connection, is equivalent to a non-degenerate solution of the c-projectively invariant metrizability…

Differential Geometry · Mathematics 2022-01-03 Keegan J. Flood , A. Rod Gover

The mobility of a Kaehler metric is the dimension of the space of metrics with which it is c-projectively equivalent. The mobility is at least two if and only if the Kaehler metric admits a nontrivial hamiltonian 2-form. After summarizing…

Differential Geometry · Mathematics 2019-02-20 David M. J. Calderbank , Vladimir S. Matveev , Stefan Rosemann

In this paper, we will prove subadditivity of Kodaira dimensions for a fibration with possibly singular geometric generic fiber, under certain nefness and relative semi-ampleness conditions. As an application, for a fibration $f: X \to Y$…

Algebraic Geometry · Mathematics 2019-07-18 Lei Zhang

Let X be a compact hyperk\"ahler manifold containing a complex torus L as a Lagrangian subvariety. Beauville posed the question whether X admits a Lagrangian fibration with fibre L. We show that this is indeed the case if X is not…

Algebraic Geometry · Mathematics 2021-08-31 Daniel Greb , Christian Lehn , Sönke Rollenske

We apply the combinatorial theory of spherical varieties to characterize the momentum polytopes of polarized projective spherical varieties. This enables us to derive a classification of these varieties, without specifying the open orbit,…

Algebraic Geometry · Mathematics 2020-04-16 Stéphanie Cupit-Foutou , Guido Pezzini , Bart Van Steirteghem

In this note a natural strengthening of internality motivated by complex geometry, being "Moishezon" to a set of types, is introduced. Under the hypothesis of Pillay's canonical base property, and using results of Chatzidakis, a criterion…

Logic · Mathematics 2015-03-17 Rahim Moosa

We classify all smooth compact connected K\"ahler threefolds that admit the structure of a $C^\infty$-fiber bundle over the circle. This generalizes the work of Hao and Schreieder in the projective case. In contrast to the projective case,…

Algebraic Geometry · Mathematics 2025-06-30 Simon Pietig

The semistable minimal model program is a special case of the minimal model program concerning 3-folds fibred over a curve and birational morphisms preserving this structure. We classify semistable divisorial contractions which contract the…

Algebraic Geometry · Mathematics 2010-03-16 Paul Hacking

A result due to Cho, Miyaoka, Shepherd-Barron [CMSB] and Kebekus [Ke] provides a numerical characterization of projective spaces. More recently, Dedieu and H\"oring [DH] gave a characterization of smooth quadrics based on similar arguments.…

Algebraic Geometry · Mathematics 2024-11-27 Bruno Dewer

We develop in detail the theory of c-projective geometry, a natural analogue of projective differential geometry adapted to complex manifolds. We realise it as a type of parabolic geometry and describe the associated Cartan or tractor…

Differential Geometry · Mathematics 2021-06-08 David M. J. Calderbank , Michael G. Eastwood , Vladimir S. Matveev , Katharina Neusser

Two Kaehler metrics on one complex manifold are said to be c-projectively equivalent if their J-planar curves, i.e., curves defined by the property that their acceleration is complex proportional to their velocity, coincide. The degree of…

Differential Geometry · Mathematics 2015-10-02 Vladimir S. Matveev , Stefan Rosemann

Let $\mathcal{G} \rightrightarrows M$ be a source locally trivial proper Lie groupoid such that each orbit is of finite type. The orbit projection $M \to M/\mathcal{G}$ is a fibration if and only if $\mathcal{G} \rightrightarrows M$ is…

Differential Geometry · Mathematics 2010-03-30 Armin Rainer