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Let $f: X\to Y$ be a proper surjective morphism of varieties defined over an algebraically closed field of positive characteristic. We prove that if $f$ has geometrically connected fibers then the induced homomorphism of $F$-divided…

Algebraic Geometry · Mathematics 2026-01-27 Adrian Langer

We study the affine quasi-Einstein Equation for homogeneous surfaces. This gives rise through the modified Riemannian extension to new half conformally flat generalized quasi-Einstein neutral signature $(2,2)$ manifolds, to conformally…

Differential Geometry · Mathematics 2017-07-21 Miguel Brozos-Vázquez , Eduardo García-Río , Peter Gilkey , Xabier Valle-Regueiro

The orbital varieties are the irreducible components of the intersection between a nilpotent orbit and a Borel subalgebra of the Lie algebra of a reductive group. There is a geometric correspondence between orbital varieties and irreducible…

Representation Theory · Mathematics 2018-10-31 Lucas Fresse , Anna Melnikov

Since for the classification of finite (congruence-)simple semirings it remains to classify the additively idempotent semirings, we progress on the characterization of finite simple additively idempotent semirings as semirings of…

Rings and Algebras · Mathematics 2013-01-01 Andreas Kendziorra , Jens Zumbrägel

We prove that the bounded derived category of coherent sheaves on a smooth projective complex variety reconstructs the isomorphism classes of fibrations onto smooth projective curves of genus $g\geq 2$. Moreover, in dimension at most four,…

Algebraic Geometry · Mathematics 2023-09-14 Luigi Lombardi

A projective link is a smooth closed 1-submanifold of the real projective space of dimension three. A projective link is said to be affine if it is isotopic to a link, which does not intersect some projective plane. The main result: a…

Geometric Topology · Mathematics 2019-01-24 Oleg Viro

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 prove uniform boundedness statements for semistable pure sheaves on projective manifolds. For example, we prove that the set of isomorphism classes of pure sheaves of dimension 2 that are slope semistable with respect to ample classes…

Algebraic Geometry · Mathematics 2024-03-20 Mihai Pavel , Julius Ross , Matei Toma

We prove that any open subset $U$ of a semi-simple simply connected quasi-split linear algebraic group $G$ with ${codim} (G\setminus U, G)\geq 2$ over a number field satisfies strong approximation by establishing a fibration of $G$ over a…

Algebraic Geometry · Mathematics 2018-05-22 Yang Cao , Yongqi Liang , Fei Xu

This submission replaces the arXiv:1012.5381 submission with the same title, which had been withdrawn as it contained a mistake, repaired in this submission: on $X$ projective smooth over an algebraically closed field of characteristic…

Algebraic Geometry · Mathematics 2011-12-21 Hélène Esnault , Xiaotao Sun

We consider when a smooth vector bundle endowed with a connection possesses non-trivial, local parallel sections. This is accomplished by means of a derived flag of subsets of the bundle. The procedure is algebraic and rests upon the…

Differential Geometry · Mathematics 2008-04-11 Richard Atkins

In \cite{FMX19}, it is proved that the convolution algebra of top Borel-Moore homology on Steinberg variety of type $B/C$ realizes $U(sl_n^{\theta})$, where $sl_{n}^{\theta}$ is the fixed point subalgebra of involution on $sl_n$. So top…

Representation Theory · Mathematics 2021-08-31 Zhijie Dong , Haitao Ma

We classify smooth surfaces whose higher cohomologies of i-forms for all i vanish. We show that if such a surface is not affine, then it has essentially two possibilities.

alg-geom · Mathematics 2008-02-03 N. Mohan Kumar

We prove three results on pure resolutions of vector bundles on projective spaces. First, we show that there are simple vector bundles of rank n on Pn with arbitrary homological dimension. We then analyze the pure resolutions given by the…

Algebraic Geometry · Mathematics 2012-10-31 Marcos Jardim , Daniela Moura Prata

Let $n$ be a positive integer. The main result of this manuscript is a construction of a filtration on the cohomology ring of a regular nilpotent Hessenberg variety in $GL(n,{\mathbb{C}})/B$ such that its associated graded ring has graded…

Algebraic Geometry · Mathematics 2020-03-12 Megumi Harada , Tatsuya Horiguchi , Satoshi Murai , Martha Precup , Julianna Tymoczko

We study smooth bundles over surfaces with highly connected almost parallelizable fiber $M$ of even dimension, providing necessary conditions for a manifold to be bordant to the total space of such a bundle and showing that, in most cases,…

Algebraic Topology · Mathematics 2022-02-10 Manuel Krannich , Jens Reinhold

Let $(M,g)$ be a closed oriented negatively curved surface. A unitary connection on a Hermitian vector bundle over $M$ is said to be transparent if its parallel transport along the closed geodesics of $g$ is the identity. We study the space…

Differential Geometry · Mathematics 2010-05-12 Gabriel P. Paternain

We show that tensor products of semiample vector bundles are semiample. For k-ampleness in the sens of Sommese, we show that over compact complex manifolds tensor products of semiample and k-ample vector bundles are k-ample, and the sum of…

Algebraic Geometry · Mathematics 2016-07-26 F. Laytimi , W. Nahm

For any subgroup of $\mathrm{SL}(3,\mathbb{R})\ltimes\mathbb{R}^3$ obtained by adding a translation part to a subgroup of $\mathrm{SL}(3,\mathbb{R})$ which is the fundamental group of a finite-volume convex projective surface, we first show…

Differential Geometry · Mathematics 2023-07-04 Xin Nie , Andrea Seppi

We prove that the coherent Springer sheaf and its parabolic analogues are concentrated in cohomological degree $0$, as predicted by Ben-Zvi-Chen-Helm-Nadler, Zhu, Emerton-Gee-Hellmann, Hansen, and others. More generally, we show that the…

Representation Theory · Mathematics 2026-02-23 Oron Y. Propp