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Related papers: Moishezon manifolds with no nef and big classes

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Let X be a compact Kaehler threefold with terminal singularities such that K\_X is nef. We prove that K\_X is semiample.

Algebraic Geometry · Mathematics 2015-04-21 Frédéric Campana , Andreas Hoering , Thomas Peternell

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 classify compact simply-connected 5-dimensional manifolds which admit a metric of nonnegative curvature with a connected non-abelian group acting by isometries. We show that they are diffeomorphic to either S^5, S^3 x S^2, the nontrivial…

Differential Geometry · Mathematics 2012-12-21 Fabio Simas

Let $X$ be a compact orientable non-Haken 3-manifold modeled on the Thurston geometry $\text{Nil}$. We show that the diffeomorphism group $\text{Diff}(X)$ deformation retracts to the isometry group $\text{Isom}(X)$. Combining this with…

Differential Geometry · Mathematics 2023-09-12 Richard H. Bamler , Bruce Kleiner

Let X be an irreducible symplectic manifold and L a nef line bundle on X which is isotropic with respect to the Beauville-Bogomolov quadratic form. It is known that a subgroup Aut(X,L) of an automorphism group of X which fix L is almost…

Algebraic Geometry · Mathematics 2018-12-31 Daisuke Matsushita

Given a compact K\"ahler manifold $X$ it is interesting to ask whether it admits a constant scalar curvature K\"ahler (cscK) metric. In this short note we show that there always exist cscK metrics on compact K\"ahler manifolds with nef…

Differential Geometry · Mathematics 2020-12-01 Zakarias Sjöström Dyrefelt

We first prove an isomorphism between the moduli space of smooth cubic threefolds and the moduli space of hyperkaehler fourfolds of K3^{[2]}-type with a non-symplectic automorphism of order three, whose invariant lattice has rank one and is…

Algebraic Geometry · Mathematics 2018-01-30 Samuel Boissière , Chiara Camere , Alessandra Sarti

In this paper, for compact K\"ahler manifolds with nef cotangent bundle, we study the abundance conjecture and the associated Iitaka fibrations. We show that, for a minimal compact K\"ahler manifold, the second Chern class vanishes if and…

Algebraic Geometry · Mathematics 2022-05-24 Masataka Iwai , Shin-ichi Matsumura

We give examples of closed, oriented 3-manifolds whose fundamental groups are not isomorphic, but yet have the same sets of finite quotient groups; hence the same profinite completions. We also give examples of compact, oriented 3-manifolds…

Geometric Topology · Mathematics 2014-10-06 John Hempel

Let M be a closed 3-manifold which can be triangulated with N simplices. We prove that any map from M to a genus 2 surface has Hopf invariant at most C^N. Let X be a closed oriented hyperbolic 3-manifold with injectivity radius less than…

Differential Geometry · Mathematics 2009-03-16 Larry Guth

We describe MBM classes for irreducible holomorphic symplectic manifolds of K3 and Kummer types. These classes are the monodromy images of extremal rational curves which give the faces of the nef cone of some birational model. We study the…

Algebraic Geometry · Mathematics 2025-04-21 Anastasia V. Vikulova

Let $ 1 \rightarrow N \rightarrow G \rightarrow Q \rightarrow 1$ be an exact sequence of finitely presented groups where Q is infinite and not virtually cyclic, and is the fundamental group of some closed 3-manifold. If G is Kaehler, we…

Geometric Topology · Mathematics 2012-12-14 Indranil Biswas , Mahan Mj , Harish Seshadri

Given a surjective holomorphic map between two compact Kaehler manifolds, we investigate the positivity properties of relative adjoint transcendental classes which are inherited from similar fiberwise properties. As a consequence, we solve…

Complex Variables · Mathematics 2012-09-12 Mihai Paun

This paper shows that the Seifert volume of each closed non-trivial graph manifold is virtually positive. As a consequence, for each closed orientable prime 3-manifold $N$, the set of mapping degrees $\c{D}(M,N)$ is finite for any…

Geometric Topology · Mathematics 2014-02-26 Pierre Derbez , Shicheng Wang

We show that a compact complex parallelisable nilmanifold has unobstructed deformations if and only if its associated Lie algebra satisfies a reality condition and is a free Lie algebra in a variety of Lie algebras, that is, defined by a…

Differential Geometry · Mathematics 2024-11-27 Matthias Paulsen , Sönke Rollenske , Konstantin Wehler

In this article we studied Nielsen coincidence theory for maps between manifolds of same dimension without hypotheses on orientation. We use the definition of semi-index of a class, we review the definition of defective classes and study…

Algebraic Topology · Mathematics 2007-05-23 Daniel Vendrúscolo

Essential $\aleph_0$-categoricity; i.e., $\aleph_0$-categoricity in some full countable language, is shown to be a robust notion for strongly minimal compact complex manifolds. Characterisations of triviality and essential…

Logic · Mathematics 2010-07-06 Rahim Moosa , Anand Pillay

We construct two non isomorphic contractible affine threefolds X and Y with isomorphic cylinders, showing that the generalized Cancellation Problem has a negative answer in general for contractible affine threefolds. We also establish that…

Algebraic Geometry · Mathematics 2015-03-17 Adrien Dubouloz , Lucy Moser-Jauslin , Pierre-Marie Poloni

For every algebraically closed field $k$ and natural number $r$, we construct several algebraic varieties (over $k$) whose birational automorphism group contains every finite nilpotent group of class at most $2$, rank at most $r$ whose…

Algebraic Topology · Mathematics 2025-10-20 Dávid R. Szabó

Given a polynomial endomorphism F of the n-dimensional affine space over a field K, we define a sequence of polynomial endomorphisms of the affine space associated to F. We call F nice if there exists an integer m such that the m-th term of…

Algebraic Geometry · Mathematics 2016-01-07 Elzbieta Adamus , Pawel Bogdan , Teresa Crespo , Zbigniew Hajto