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We define partially ample subvarieties of projective varieties, generalizing Ottem's work on ample subvarieties, and show their ubiquity. As an application, we obtain a connectedness result for pre-images of subvarieties by morphisms,…

Algebraic Geometry · Mathematics 2018-05-21 Mihai Halic

The cotangent bundle of a non-uniruled projective manifold is generically nef, due to a theorem of Miyaoka. We show that the cotangent bundle is actually generically ample, if the manifold is of general type and study in detail the case of…

Algebraic Geometry · Mathematics 2011-06-22 Thomas Peternell

We prove a non-vanishing theorem of the cohomology H^0 of the adjoint divisor K_X + L' where L' is the round up of a nef and big Q-divisor L.

Algebraic Geometry · Mathematics 2007-05-23 Jungkai Alfred Chen , Meng Chen , De-Qi Zhang

In this note I extend two theorems of Sommese regarding abelian varieties to arbitrary characteristic; that an abelian variety cannot be an ample divisor in a smooth projective variety and that a cone over an abelian variety of dimension at…

Algebraic Geometry · Mathematics 2019-12-17 Sándor J Kovács

We prove an elegant structure theorem for log de Rham-Witt sheaves with vanishing along an effective Cartier divisor $D$ defined in arXiv:2403.18763, answering a question of Shuji Saito during the Mainz conference and a question of Yigeng…

Algebraic Geometry · Mathematics 2025-05-02 Fei Ren

We study a class of continuous deformations of branched complex projective structures on closed surfaces of genus $g\geq 2$, which preserve the holonomy representation of the structure and the order of the branch points. In the case of…

Complex Variables · Mathematics 2021-03-25 Stefano Francaviglia , Lorenzo Ruffoni

In this paper, we develop the general intersection theory of nef b-divisors, extending the movable intersection theory. We define a notion of restricted volume of b-divisors and prove a quantitative version of the monotonicity of the…

Algebraic Geometry · Mathematics 2026-03-17 Mingchen Xia

We apply Schmidt's Subspace Theorem to establish Arithmetic General Theorems for projective varieties over number and function fields. Our first result extends an analogous result of M. Ru and P. Vojta. One aspect to its proof makes use of…

Algebraic Geometry · Mathematics 2018-09-05 Nathan Grieve

We exhibit invariants of smooth projective algebraic varieties with integer values, whose nonvanishing modulo p prevents the existence of an action without fixed points of certain finite p-groups. The case of base fields of characteristic p…

Algebraic Geometry · Mathematics 2019-02-20 Olivier Haution

We consider subtorus actions on divisorial toric varieties. Here divisoriality means that the variety has many Cartier divisors like quasiprojective and smooth ones. We characterize when a subtorus action on such a toric variety admits a…

Algebraic Geometry · Mathematics 2007-05-23 A. A'Campo-Neuen , J. Hausen

This paper gives an explicit computation of the category of constructible sheaves on a toric variety (with respect to the stratification by torus orbits). Over the complex numbers, this simplifies a description due to Braden and Lunts. The…

Algebraic Geometry · Mathematics 2024-10-10 Remy van Dobben de Bruyn

We define and study positivity (nefness, amplitude, bigness and pseudo-effectiveness) for Weil divisors on normal projective varieties. We prove various characterizations, vanishing and non-vanishing theorems for cohomology, global…

Algebraic Geometry · Mathematics 2015-05-06 Alberto Chiecchio , Stefano Urbinati

We show that smooth projective horospherical varieties with nef tangent bundles are rational homogeneous spaces.

Algebraic Geometry · Mathematics 2015-12-16 Qifeng Li

We show that varieties of dimension at least 2 over infinite fields are determined as abstract schemes by their Zariski topological spaces together with the rational equivalence relation on the set of effective divisors. This gives a…

Algebraic Geometry · Mathematics 2020-04-28 Max Lieblich , Martin Olsson

We give a geometric proof of Conn's linearization theorem for analytic Poisson structures, without using the fast convergence method.

Symplectic Geometry · Mathematics 2007-05-23 Nguyen Tien Zung

We show that the hypercohomology of most character twists of perverse sheaves on a complex abelian variety vanishes in all non-zero degrees. As a consequence we obtain a vanishing theorem for constructible sheaves and a relative vanishing…

Algebraic Geometry · Mathematics 2015-10-01 Thomas Krämer , Rainer Weissauer

We introduce a notion of constructibility for \'etale sheaves with torsion coefficients over a suitable class of adic spaces. This notion is related to the classical notion of constructibility for schemes via the nearby cycles functor. We…

Algebraic Geometry · Mathematics 2017-07-13 Ildar Gaisin , John Welliaveetil

In this paper, we establish a structure theorem for minimal projective klt varieties $X$ that satisfiy Miyaoka's equality $3c_2(X) = c_1(X)^2$. Specifically, we prove that the canonical divisor $K_X$ is semi-ample and that the Kodaira…

Algebraic Geometry · Mathematics 2025-10-23 Masataka Iwai , Shin-ichi Matsumura , Niklas Müller

It is expected that a totally invariant divisor of a non-isomorphic endomorphism of the complex projective space is a union of hyperplanes. In this paper, we compute an upper bound for the degree of such a divisor. As a consequence, we…

Algebraic Geometry · Mathematics 2021-11-30 Mabed Yanis

We first prove Vojta's abc conjecture over function fields for Campana points on projective toric varieties with high multiplicity along the boundary. As a consequence, we obtain a version of Campana's conjecture on finite coverings of…

Algebraic Geometry · Mathematics 2025-11-04 Carlo Gasbarri , Ji Guo , Julie Tzu-Yueh Wang