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We show that for a surjective, separable morphism f of smooth projective varieties over an algebraically closed field of positive characteristic such that $f_* \mathcal{O}_X = \mathcal{O}_Y$ subadditivity of Kodaira dimension holds,…

Algebraic Geometry · Mathematics 2014-03-06 Zsolt Patakfalvi

For a reduced pure dimensional complex space $X$, we show that if Barlet's recently introduced sheaf $\alpha_X^1$ of holomorphic $1$-forms or the sheaf of germs of weakly holomorphic $1$-forms is locally free, then $X$ is smooth. Moreover,…

Complex Variables · Mathematics 2020-05-18 Håkan Samuelsson Kalm , Martin Sera

Let $X$ be a projective variety with log terminal singularities and vanishing augmented irregularity. In this paper we prove that if $X$ admits a relatively minimal genus one fibration then it does contain a subvariety of codimension one…

Algebraic Geometry · Mathematics 2019-03-14 Fabrizio Anella

We generalize a result of Orlov and Van den Bergh on the representability of a cohomological functor from the bounded derived category of a smooth projective variety over a field to the category of L-modules, to the case where L is a field…

Algebraic Geometry · Mathematics 2014-02-20 Alice Rizzardo

We prove that a normal variety contains finitely many maximal quasi-projective open subvarieties. As a corollary, we obtain the following generalization of the Chevalley-Kleiman projectivity criterion : a normal variety is quasi-projective…

Algebraic Geometry · Mathematics 2019-11-11 Olivier Benoist

We consider correspondences on smooth quasiprojective varieties $U$. An algebraic cycle inducing the K\"unneth projector onto $H^1(U)$ is constructed. Assuming normal crossings at infinity, the existence of relative motivic cohomology is…

Algebraic Geometry · Mathematics 2007-05-23 Spencer Bloch , Hélène Esnault

This article contains a new argument which proves vanishing of the first cohomology for negative vector bundles over a complex projective variety if the rank of the bundle is smaller than the dimension of the base. Similar argument is…

Algebraic Geometry · Mathematics 2007-05-23 Fedor Bogomolov

Grothendieck has proved that each class in the de Rham cohomology of a smooth complex affine variety can be represented by a differential form with polynomial coefficients. After having proved a single exponential bound for the degrees of…

Algebraic Geometry · Mathematics 2018-11-08 Peter Scheiblechner

We give a cohomological classification of vector bundles of rank $2$ on a smooth affine threefold over an algebraically closed field having characteristic unequal to $2$. As a consequence we deduce that cancellation holds for rank $2$…

Algebraic Geometry · Mathematics 2015-01-14 Aravind Asok , Jean Fasel

In this paper we introduce the notion of deformation cohomology for singular foliations and related objects (namely integrable differential forms and Nambu structures), and study it in the local case, i.e., in the neighborhood of a point.

Differential Geometry · Mathematics 2019-04-16 Philippe Monnier , Nguyen Tien Zung

We prove a cohomological splitting result for Hamiltonian fibrations over enumeratively rationally connected symplectic manifolds As a key application, we prove that the cohomology of a smooth, projective family over a smooth (stably)…

Symplectic Geometry · Mathematics 2024-07-08 Shaoyun Bai , Daniel Pomerleano , Guangbo Xu

Using results of Gathmann, we prove the following theorem: If a smooth projective variety X has generically semisimple (p,p)-quantum cohomology, then the same is true for the blow-up of X at any number of points. This a successful test for…

Algebraic Geometry · Mathematics 2012-04-06 Arend Bayer

We show various properties of smooth projective D-affine varieties. In particular, any smooth projective D-affine variety is algebraically simply connected and its image under a fibration is D-affine. In characteristic zero such D-affine…

Algebraic Geometry · Mathematics 2023-01-31 Adrian Langer

We answer a question of Koll\'ar and Kov\'acs by constructing a flat projective morphism to a smooth curve whose fibers are Cohen--Macaulay and reduced, whose generic fiber is smooth, and for which the first cohomology of the structure…

Algebraic Geometry · Mathematics 2026-05-21 Jihao Liu

We compute the sheaf cohomology with constant $\mathbb{Z}_2$ coefficients of a concrete class of locally profinite sets of independent interest. We introduce $k$-sheer partitions to aid in constructions. It is also shown that questions of…

Logic · Mathematics 2026-04-14 Mark Schachner

In the present article we define an integral analogue of Chow-K\"unneth decomposition for \'etale motives. By using families of conservative functors we are able to establish a decomposition of the \'etale motive of commutative group…

Algebraic Geometry · Mathematics 2024-03-04 Ivan Rosas-Soto

We consider the category $\operatorname{Qcoh}\mathbb{X}$ of quasicoherent sheaves where $\mathbb{X}$ is a weighted noncommutative regular projective curve over a field $k$. This category is a hereditary, locally noetherian Grothendieck…

Representation Theory · Mathematics 2020-09-28 Dirk Kussin , Rosanna Laking

We compute Hochschild cohomology of projective hypersurfaces starting from the Gerstenhaber-Schack complex of the (restricted) structure sheaf. We are particularly interested in the second cohomology group and its relation with…

Algebraic Geometry · Mathematics 2016-02-15 Liyu Liu , Wendy Lowen

We study the singularities of secant varieties of smooth projective varieties using methods from birational geometry when the embedding line bundle is sufficiently positive. More precisely, we study the Du Bois complex of secant varieties…

Algebraic Geometry · Mathematics 2024-08-22 Sebastian Olano , Debaditya Raychaudhury , Lei Song

Chow's Theorem and GAGA are renowned results demonstrating the algebraic nature of projective manifolds and, more broadly, projective analytic varieties. However, determining if a particular manifold is projective is not, generally, a…

Algebraic Geometry · Mathematics 2025-01-14 Skyler Marks