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We prove some triviality results for reduced Whitehead groups and reduced unitary Whitehead groups for division algebras over a henselian discrete valuation field whose residue field has virtual cohomological dimension or separable…

Number Theory · Mathematics 2025-07-24 Yong Hu , Yisheng Tian

We extend Tate duality for Galois cohomology of abelian varieties to $1$-motives over a $p$-adic field, improving a result of Harari and Szamuely. To do this, we replace Galois cohomology with the condensed cohomology of the Weil group.…

Number Theory · Mathematics 2025-03-19 Marco Artusa

Inspired by Emerton's work for GL(2), we study the completed cohomology of the tower of finite sets associated with a definite unitary group in two variables. When p splits (and other technical assumptions are fulfilled), we show that the…

Number Theory · Mathematics 2013-04-18 Przemyslaw Chojecki , Claus Sorensen

In this paper we show that weak Hopf (co)quasigroups can be characterized by a Galois-type condition. Taking into account that this notion generalizes the ones of Hopf (co)quasigroup and weak Hopf algebra, we obtain as a consequence the…

Quantum Algebra · Mathematics 2015-06-26 J. N. Alonso Álvarez , J. M. Fernández Vilaboa , R. González Rodríguez

Semi-topological Galois theory associates a canonical finite splitting covering to a monic Weierstrass polynomial. The inverse limit of the corresponding deck groups defines the absolute semi-topological Galois group, $\PiST(X,x)$. This…

Algebraic Topology · Mathematics 2026-03-05 Jyh-Haur Teh

In this expository article, we outline a basic theory of group (co)homology and prove a cohomological formulation of the Local Reciprocity Law: $${\rm Gal}(L/K)^{\rm ab} \cong H_T^{-2}({\rm Gal}(L/K),\mathbb{Z}) \cong H_T^{0}({\rm…

Number Theory · Mathematics 2024-05-27 Uzu Lim

The theory of p-ramification, regarding the Galois group of the maximal pro-p-extension of a number field K, unramified outside p and $\infty$, is well known including numerical experiments with PARI/GP programs. The case of ``incomplete…

Number Theory · Mathematics 2021-08-06 Georges Gras

In this paper we investigate the cohomological obstruction for the field of moduli of a $G$-cover to be a field of definition, in the case of local fields and covers with tame admissible reduction. This applies in particular to $p$-adic…

Algebraic Geometry · Mathematics 2009-09-25 Stefan Wewers

In Proposition I of "Memoire sur les conditions de resolubilite des equations par radicaux", Galois established that any intermediate extension of the splitting field of a polynomial with rational coefficients is the fixed field of its…

Category Theory · Mathematics 2007-05-23 Eduardo J. Dubuc

If T is an algebraic torus defined over a discretely valued field K with perfect residue field k, we relate the K-cohomology of T to the k-cohomology of certain objects associated to T. When k has cohomological dimension <= 1, our results…

Number Theory · Mathematics 2013-12-04 Alessandra Bertapelle , Cristian D. Gonzalez-Aviles

We compute equivariant Euler characteristics of locally free sheaves on curves, thereby generalizing several results of Kani and Nakajima. For instance, we extend Kani's computation of the Galois module structure of the space of global…

Algebraic Geometry · Mathematics 2007-05-23 Bernhard Köck

We discuss the Capitulation Problem for Neron-Raynaud class groups of tori over global fields F and obtain generalizations of the main results of [10]. We also show that short exact sequences of F-tori induce long exact sequences involving…

Number Theory · Mathematics 2009-03-19 Cristian D. Gonzalez-Aviles

In this article I define and study the overconvergent rigid fundamental group of a variety over an equicharacteristic local field. This is a non-abelian $(\varphi,\nabla)$-module over the bounded Robba ring $\mathcal{E}_K^\dagger$, whose…

Number Theory · Mathematics 2017-06-15 Christopher Lazda

Motivated by its links to $\tau$-tilting theory, we introduce a generalization of cotorsion pairs in module categories. Such pairs are also linked to co-t-structures in corresponding triangulated categories, and to cotorsion pairs in…

Representation Theory · Mathematics 2021-11-23 Aslak Bakke Buan , Yu Zhou

We study deformation theory of mod $p$ Galois representations of $p$-adic fields with values in generalised tori, such as $L$-groups of (possibly non-split) tori. We show that the corresponding deformation rings are formally smooth over a…

Number Theory · Mathematics 2025-02-26 Vytautas Paškūnas , Julian Quast

Given a Galois cover of curves over $\mathbb{F}_p$, we relate the $p$-adic valuation of epsilon constants appearing in functional equations of Artin L-functions to an equivariant Euler characteristic. Our main theorem generalises a result…

Number Theory · Mathematics 2019-02-22 Helena Fischbacher-Weitz , Bernhard Köck , Adriano Marmora

For exact symplectic twist maps of the annulus, we etablish a choice of weak K.A.M. solutions $u_c=u(\cdot, c)$ that depend in a Lipschitz-continuous way on the cohomology class $c$. This allows us to make a bridge between weak K.A.M.…

Dynamical Systems · Mathematics 2022-09-26 Marie-Claude Arnaud , Maxime Zavidovique

Smooth irreducible representations of tori over local fields have been parameterized by Langlands, using class field theory and Galois cohomology. This paper extends this parameterization to central extensions of such tori, which arise…

Representation Theory · Mathematics 2008-03-13 Martin H. Weissman

We use the theory of Condensed Mathematics to build a condensed cohomology theory for the Weil group of a $p$-adic field. The cohomology groups are proved to be locally compact abelian groups of finite ranks in some special cases. This…

Number Theory · Mathematics 2025-03-19 Marco Artusa

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