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In this paper, we give a necessary and sufficient condition for the finiteness of Galois cohomology of unipotent groups over local fields of positive characteristic

Number Theory · Mathematics 2011-08-31 Nguyen Duy Tan

This paper proves local-global principles for Galois cohomology groups over function fields $F$ of curves that are defined over a complete discretely valued field. We show in particular that such principles hold for $H^n(F, Z/mZ(n-1))$, for…

Number Theory · Mathematics 2013-04-11 David Harbater , Julia Hartmann , Daniel Krashen

We study abelian varieties and K3 surfaces with complex multiplication defined over number fields of fixed degree. We show that these varieties fall into finitely many isomorphism classes over an algebraic closure of the field of rational…

Algebraic Geometry · Mathematics 2019-02-20 Martin Orr , Alexei N. Skorobogatov

In this paper, we study an analogue of the Tate conjecture for $K_2$ of U, the complement of split multiplicative fibers in an elliptic surface. A main result is to give an upper bound of the rank of the Galois fixed part of the etale…

Algebraic Geometry · Mathematics 2010-09-07 Masanori Asakura , Kanetomo Sato

In this paper, we define a generalization of the Brauer groups by using Bloch's cycle complex on etale site. We prove the Gersten conjecture of generalized Brauer group on some cases. As an application we prove the Gersten conjecture of the…

Number Theory · Mathematics 2016-11-08 Makoto Sakagaito

This article is a survey of conjectures and results on reductive algebraic groups having good reduction at a suitable set of discrete valuations of the base field. Until recently, this subject has received relatively little attention, but…

Number Theory · Mathematics 2020-08-18 Andrei S. Rapinchuk , Igor A. Rapinchuk

The Lichtenbaum-Quillen conjecture for smooth complex varieties states that algebraic and topological K-theory with finite coefficients become isomorphic in high degrees. We define the "Lichtenbaum-Quillen dimension" of a variety in terms…

Algebraic Geometry · Mathematics 2026-04-14 Nicolas Addington , Elden Elmanto

We study Gushel-Mukai (GM) varieties of dimension 4 or 6 in characteristic $p$. Our main result is the Tate conjecture for all such varieties over finitely generated fields of characteristic $p\geq 5$. In the case of GM sixfolds, we follow…

Algebraic Geometry · Mathematics 2024-11-19 Lie Fu , Ben Moonen

Let X be a smooth projective curve of genus >1 over a field K which is finitely generated over the rationals. The section conjecture in Grothendieck's anabelian geometry says that the sections of the canonical projection from the arithmetic…

Algebraic Geometry · Mathematics 2007-05-23 Jochen Koenigsmann

For $X$ a smooth projective variety over a field $k$, we consider the problem of Galois descent for higher Brauer groups. More precisely, we extend a finiteness result of Colliot-Th\'el\`ene and Skorobogatov to higher Brauer groups.

Algebraic Geometry · Mathematics 2020-11-09 Humberto A. Diaz

We make further observations on the features of Galois cohomology in the general model theoretic context. We make explicit the connection between forms of definable groups and first cohomology sets with coefficients in a suitable…

Logic · Mathematics 2021-05-28 Omar Leon Sanchez , David Meretzky , Anand Pillay

We prove that the triviality of the Galois action on the suitably twisted odd-dimensional \'etale cohomogy group of a smooth projective varietiy with finite coefficients implies the existence of certain primitive roots of unity in the field…

Algebraic Geometry · Mathematics 2016-06-02 Yuri G. Zarhin

This paper investigates the structure of generic motives and their implications for the motivic cohomology of fields. Originating in Voevodsky's theory of motives and related to Beilinson's vision of a motivic $t$-structure, generic motives…

Algebraic Geometry · Mathematics 2025-07-22 F. Déglise

The object of study is the group of units O^\ast(X) in the coordinate ring of a normal affine variety X over an algebraically closed field k. Methods of Galois cohomology are applied to those varieties that can be presented as a finite…

Algebraic Geometry · Mathematics 2016-12-05 Timothy J. Ford

Let $k$ be a finite field, a $p$-adic field or a number field. Let $K$ be a finite extension of the Laurent series field in $m$ variables $k((x_1,...,x_m))$ or, more generally, a finite extension of the field of rational functions…

Algebraic Geometry · Mathematics 2018-06-08 Diego Izquierdo

We employ the formalism of vanishing cycles and perverse sheaves to introduce and study the vanishing cohomology of complex projective hypersurfaces. As a consequence, we give upper bounds for the Betti numbers of projective hypersurfaces,…

Algebraic Geometry · Mathematics 2022-09-15 Laurenţiu Maxim , Laurenţiu Păunescu , Mihai Tibăr

Our investigation focuses on an additive analogue of the Bloch-Gabber-Kato theorem which establishes a relation between the Milnor $K$-group of a field of positive characteristic and a Galois cohomology group of the field. Extending the…

K-Theory and Homology · Mathematics 2024-09-04 Toshiro Hiranouchi

In this paper we prove the Mumford-Tate conjecture in degree 2 for the product of an abelian surface $A$ and a K3 surface $X$ over a finitely generated field $K \subset \mathbb{C}$. The Mumford-Tate conjecture is a precise way of saying…

Algebraic Geometry · Mathematics 2017-09-11 Johan Commelin

Let $k$ be a field that is finitely generated over the field of rational numbers and $Br(k)$ the Brauer group of $k$. Let $X$ be an absolutely irreducible smooth projective variety over $k$, let $Br(X)$ be the cohomological…

Number Theory · Mathematics 2007-11-05 Alexei Skorobogatov , Yuri Zarhin

Duality for complete discrete valuation fields with perfect residue field with coefficients in (possibly p-torsion) finite flat group schemes was obtained by Begueri, Bester and Kato. In this paper, we give another formulation and proof of…

Number Theory · Mathematics 2022-11-21 Takashi Suzuki