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We introduce a spherical variant of Milnor's classifying construction for diffeological groups, based on quadratic normalization of barycentric coordinates. This construction gives rise to a contractible diffeological space endowed with…

Differential Geometry · Mathematics 2026-05-19 Jean-Pierre Magnot

In this article, we study projective log smooth pairs with numerically flat normalized logarithmic tangent bundle. Generalizing works of Jahnke-Radloff and Greb-Kebekus-Peternell, we show that, passing to an appropriate finite cover and up…

Algebraic Geometry · Mathematics 2021-12-13 Stéphane Druel

We study smooth projective complex varieties with ample cotangent bundle. Our main result is that in an abelian variety of dimension n, a complete intersection of at least n/2 general hypersurfaces of sufficiently high degrees has ample…

Algebraic Geometry · Mathematics 2011-09-08 O. Debarre

This paper is devoted to rigidity of smooth bundles which are equipped with fiberwise geometric or dynamical structure. We show that the fiberwise associated sphere bundle to a bundle whose leaves are equipped with (continuously varying)…

Dynamical Systems · Mathematics 2014-07-30 F. Thomas Farrell , Andrey Gogolev

The purpose of this article is to give an interpretation of real projective structures and associated cohomology classes in terms of connections, sections, etc. satisfying elliptic partial differential equations in the spirit of Hodge…

Differential Geometry · Mathematics 2007-05-23 F. Labourie

In this paper, we obtain a complete classification of smooth toric Fano varieties equipped with extremal contractions which contract divisors to curves for any dimension. As an application, we obtain a complete classification of smooth…

Algebraic Geometry · Mathematics 2007-05-23 Hiroshi Sato

We develop a theory of conically smooth stratified spaces and their smooth moduli, including a notion of classifying maps for tangential structures. We characterize continuous space-valued sheaves on these conically smooth stratified spaces…

Algebraic Topology · Mathematics 2017-02-10 David Ayala , John Francis , Hiro Lee Tanaka

This monograph is on convex real projective structures on strongly tame n-orbifolds with some appropriate conditions on ends.

Geometric Topology · Mathematics 2025-09-03 Suhyoung Choi

In this paper, we prove that a compact K\"ahler manifold $X$ with semi-positive holomorphic sectional curvature admits a locally trivial fibration $\phi \colon X \to Y$, where the fiber $F$ is a rationally connected projective manifold and…

Differential Geometry · Mathematics 2025-02-04 Shin-ichi Matsumura

In this paper, we show an extension type theorem for twisted pluricanonical sections on a family of smooth projective manifolds (the twisting line bundle being pseudo-effective and having a prescribed multiplier ideal on the central fiber).

Algebraic Geometry · Mathematics 2016-08-16 Benoît Claudon

We investigate the logarithmic bundles associated to arrangements of hypersurfaces with a fixed degree in a smooth projective variety. We then specialize to the case when the variety is a quadric hypersurface and a multiprojective space to…

Algebraic Geometry · Mathematics 2013-12-10 Edoardo Ballico , Sukmoon Huh , Francesco Malaspina

It goes back to Ahlfors that a real algebraic curve admits a real-fibered morphism to the projective line if and only if the real part of the curve disconnects its complex part. Inspired by this result, we are interested in characterising…

Algebraic Geometry · Mathematics 2023-07-18 Mario Kummer , Cédric Le Texier , Matilde Manzaroli

We study when two projective bundles over two arbitrary smooth projective varieties of different dimensions can be isomorphic. We show that two multi-projective bundles (fibre product of projective bundles) over different projective spaces…

Algebraic Geometry · Mathematics 2023-11-03 Ashima Bansal , Supravat Sarkar , Shivam Vats

We formalize the concepts of holomorphic affine and projective structures along the leaves of holomorphic foliations by curves on complex manifolds. We show that many foliations admit such structures, we provide local normal forms for them…

Differential Geometry · Mathematics 2024-07-08 Bertrand Deroin , Adolfo Guillot

We study relative hypersurfaces over curves, and prove an instability condition for the fibres. This gives an upper bound on the log canonical threshold of the relative hypersurface. We compare these results with the information that can be…

Algebraic Geometry · Mathematics 2023-12-29 M. A. Barja , L. Stoppino

Simply-connected manifolds of positive sectional curvature $M$ are speculated to have a rigid topological structure. In particular, they are conjectured to be rationally elliptic, i.e., all but finitely many homotopy groups are conjectured…

Differential Geometry · Mathematics 2015-09-30 Manuel Amann , Lee Kennard

We study contact structures on smooth complex projective varieties with a simple normal crossing divisor, generalizing some well-known results concerning the non-logarithmic case. In particular, we describe the structure of elementary log…

Algebraic Geometry · Mathematics 2024-04-02 Adrian Langer

We consider all complex projective manifolds X that satisfy at least one of the following three conditions: 1. There exists a pair $(C ,\varphi)$, where $C$ is a compact connected Riemann surface and $\varphi : C\to X$ a holomorphic map,…

Algebraic Geometry · Mathematics 2009-01-28 Indranil Biswas

We present a number of conditions which are necessary for an n-dimensional projective structure (M,[nabla]) to include the Levi-Civita connection nabla of some metric on M. We provide an algorithm, which effectively checks if a Levi-Civita…

Differential Geometry · Mathematics 2015-05-18 Pawel Nurowski

Motivated by a conjecture of Xiao, we study supporting divisors of fibred surfaces. On the one hand, after developing a formalism to treat one-dimensional families of varieties of any dimension, we give a structure theorem for fibred…

Algebraic Geometry · Mathematics 2016-02-22 Víctor González-Alonso