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We prove that certain fields have the property that their absolute Galois groups are free as profinite groups: the function field of a real curve with no real points; the maximal abelian extension of a 2-variable Laurent series field over a…

Algebraic Geometry · Mathematics 2007-05-23 David Harbater

Let $F$ be a field with characteristic $\neq 2$. We show that $F$ is a nonrigid field if and only if certain small 2-groups occur as Galois groups over $F$. These results provide new "automatic realizability" results for Galois groups over…

Number Theory · Mathematics 2007-05-23 Wenfeng Gao , David B. Leep , Jan Minac , Tara L. Smith

Let $X$ be a smooth curve over a finitely generated field $k$, and let $\ell$ be a prime different from the characteristic of $k$. We analyze the dynamics of the Galois action on the deformation rings of mod $\ell$ representations of the…

Algebraic Geometry · Mathematics 2018-09-12 Daniel Litt

Suppose given a Galois etale cover Y -> X of proper non-singular curves over an algebraically closed field k of prime characteristic p. Let H be its Galois group, and G any finite extension of H by a p-group P. We give necessary and…

Algebraic Geometry · Mathematics 2007-05-23 Niels Borne

We formulate for function fields an analog of Serre's conjecture on the modularity of 2-dimensional irreducible mod l representations of the absolute Galois group of Q: our analog is not restricted to 2-dimensional represntations. While the…

Number Theory · Mathematics 2007-05-23 Gebhard Boeckle , Chandrashekhar Khare

The paper contains a general construction which produces new examples of non simply-connected smooth projective surfaces. We analyze the resulting surfaces and their fundamental groups. Many of these fundamental groups are expected to be…

alg-geom · Mathematics 2008-02-03 Fedor Bogomolov , Ludmil Katzarkov

We study local-global questions for Galois cohomology over the function field of a curve defined over a p-adic field (a field of cohomological dimension 3). We define Tate-Shafarevich groups of a commutative group scheme via cohomology…

Number Theory · Mathematics 2014-04-15 David Harari , Tamás Szamuely

We study the structure of the absolute differential Galois group of a rational function field over an algebraically closed field of characteristic zero. In particular, we relate the behavior of differential embedding problems to the…

Commutative Algebra · Mathematics 2022-03-22 Annette Bachmayr , David Harbater , Julia Hartmann , Michael Wibmer

Given a smooth projective curve $X$ of genus at least 2 over a number field $k$, Grothendieck's Section Conjecture predicts that the canonical projection from the \'etale fundamental group of $X$ onto the absolute Galois group of $k$ has a…

Algebraic Geometry · Mathematics 2009-04-09 David Harari , Tamas Szamuely

A main problem in Galois theory is to characterize the fields with a given absolute Galois group. We apply a K-theoretic method for constructing valuations to study this problem in various situations. As a first application we obtain an…

Number Theory · Mathematics 2007-05-23 Ido Efrat

We study the relationship between the local and global Galois theory of function fields over a complete discretely valued field. We give necessary and sufficient conditions for local separable extensions to descend to global extensions, and…

Rings and Algebras · Mathematics 2018-10-24 David Harbater , Julia Hartmann , Daniel Krashen , R. Parimala , V. Suresh

In this paper, we investigate Boston's generalization of the unramified Fontaine-Mazur conjecture for Galois representations. From a group-theoretic perspective, we first show that the conjecture can be reduced to the case of certain…

Number Theory · Mathematics 2026-01-29 Yufan Luo

We prove that function fields of varieties of dimension at least two over an algebraic closure of a finite field are determined, modulo purely inseparable extensions, by the quotient by the second term in the lower central series of their…

Algebraic Geometry · Mathematics 2009-12-31 Fedor Bogomolov , Yuri Tschinkel

We provide an infinite family of quadratic number fields with everywhere unramified Galois extensions of Galois group $SL_2(7)$. To my knowledge, this is the first instance of infinitely many such realizations for a perfect group which is…

Number Theory · Mathematics 2025-02-17 Joachim König

The article provides a sufficient condition for a locally finite module over the absolute Galois group of a finite field F to satisfy the Riemann Hypothesis Analogue with respect to the projective line. The condition holds for all smooth…

Algebraic Geometry · Mathematics 2016-08-19 Azniv Kasparian , Ivan Marinov

We show that a closed finite index subgroup of a free proalgebraic group is itself a free proalgebraic group. Our main motivation for this result is an application in differential Galois theory: The absolute differential Galois group of a…

Group Theory · Mathematics 2021-02-05 Michael Wibmer

We work over an algebraically closed field of positive characteristic. This paper investigates linear representations of Galois groups arising from wild Galois points on projective hypersurfaces. We prove that these Galois groups lift to…

Algebraic Geometry · Mathematics 2025-09-26 Taro Hayashi , Kashu Ito , Atsuya Nakajima , Keika Shimahara

Let $V$ be a projective limit, with respect to the renormalized norm mappings, of the groups of principal units corresponding to a strictly increasing sequence of finite separable totally and tamely ramified Galois extensions of a local…

Number Theory · Mathematics 2007-05-23 Anatoly N. Kochubei

In this paper, we utilize our previous results on mod p monodromy of cyclic coverings of the projective line to realize a large series of groups of the form PSL(n, q) and PSU(n, q) as Galois groups over Q. We achieve for the first time a…

Number Theory · Mathematics 2026-05-01 Stepan Nesterov

In his previous paper (Math. Res. Letters 7(2000), 123--132) the author proved that in characteristic zero the jacobian $J(C)$ of a hyperelliptic curve $C: y^2=f(x)$ has only trivial endomorphisms over an algebraic closure $K_a$ of the…

Algebraic Geometry · Mathematics 2007-05-23 Yuri G. Zarhin
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