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We consider the class of complete discretely valued fields such that the residue field is of prime characteristic p and the cardinality of a $p$-base is 1. This class includes two-dimensional local and local-global fields. A new definition…

Number Theory · Mathematics 2015-06-26 Igor B. Zhukov

We prove that the ramification filtration of the absolute Galois group of a comlete discrete valuation field with perfect residue field is characterized in terms of Fontaine's property (Pm).

Number Theory · Mathematics 2011-04-11 Manabu Yoshida

We give a characterization of ramification groups of local fields with imperfect residue fields, using those for local fields with perfect residue fields. As an application, we reprove an equality of ramification groups for abelian…

Number Theory · Mathematics 2024-10-08 Takeshi Saito

We give a purely scheme theoretic construction of the filtration by ramification groups of the Galois group of a covering. The valuation need not be discrete but the normalizations are required to be locally of complete intersection.

Algebraic Geometry · Mathematics 2018-09-12 Takeshi Saito

This is an introduction to author's ramification theory of a complete discrete valuation field with residue field whose p-basis consists of at most one element. New lower and upper filtrations are defined; cyclic extensions of degree p may…

Number Theory · Mathematics 2007-05-23 Igor Zhukov

We study the ramification groups of finite Galois extensions $L/K$ of a complete discrete valuation field $K$ of equal characteristic $p>0$ with perfect residue field and Galois group isomorphic to the group of unitriangular matrices…

Number Theory · Mathematics 2025-09-01 Koto Imai

In this article, we investigate the shift of Abbes and Saito's ramification filtrations of the absolute Galois group of a complete discrete valuation field of positive characteristic under a purely inseparable extension. We also study a…

Algebraic Geometry · Mathematics 2018-04-24 Haoyu Hu

For a finite totally ramified extension $L$ of a complete discrete valuation field $K$ with the perfect residue field of characteristic $p>0$, it is known that $L/K$ is an abelian extension if the upper ramification breaks are integers and…

Number Theory · Mathematics 2025-04-15 Taichi Inoue

This work contains a list of all known results on the quotient filtration on the Milnor K-groups of a complete discrete valuation field in terms of differential modules over the residue field . Author's recent study of the case of a tamely…

Number Theory · Mathematics 2009-09-25 Jinya Nakamura

We study the minimal number of ramified primes in Galois extensions of rational function fields over finite fields with prescribed finite Galois group. In particular, we obtain a general conjecture in analogy with the well studied case of…

Number Theory · Mathematics 2022-12-26 Lior Bary-Soroker , Alexei Entin , Arno Fehm

We examine the ramification groups of finite Galois extensions over complete discrete valuation fields of equal characteristic $p>0$. Brylinski (1983) calculated the ramification groups in the case where the Galois groups are abelian. We…

Number Theory · Mathematics 2025-09-01 Koto Imai

We prove the equality of two non-logarithmic ramification filtrations defined by Matsuda and Abbes-Saito for the abelianized absolute Galois group of a complete discrete valuation field in positive characteristic. We also compute the…

Number Theory · Mathematics 2016-09-08 Yuri Yatagawa

We classify all cubic function fields over any finite field, particularly developing a complete Galois theory which includes those cases when the constant field is missing certain roots of unity. In doing so, we find criteria which allow…

Number Theory · Mathematics 2017-05-02 Sophie Marques , Kenneth Ward

For a wildly ramified extension $K/k$ of complete discrete valuation fields we study collections of elements of $k[G]$ (where $G=Gal(K/k)$) that fit well for constructing bases of various associated Galois modules and orders. In the case…

Algebraic Geometry · Mathematics 2026-05-22 Mikhail V. Bondarko , Kirill S. Ladny , Konstantin I. Pimenov

Let K be a complete discretely valued field of mixed characteristic (0, p) with possibly imperfect residue field. We prove a Hasse-Arf theorem for the arithmetic ramification filtrations on G_K, except possibly in the absolutely unramified…

Number Theory · Mathematics 2019-02-20 Liang Xiao

Author's generalization of one-dimensional class field theory to theory of abelian totally ramified p-extensions of a complete discrete valuation field with arbitrary non-separably p-closed residue field and its applications are described.

Number Theory · Mathematics 2007-05-23 Ivan Fesenko

We specialize various three-point covers to find number fields with Galois group $M_{12}$, $M_{12}.2$, $2.M_{12}$, or $2.M_{12}.2$ and light ramification in various senses. One of our $2.M_{12}.2$ fields has the unusual property that it is…

Number Theory · Mathematics 2014-04-03 David P. Roberts

This article is devoted to studying the ramification of Galois torsors and of $\ell$-adic sheaves in characteristic $p>0$ (with $\ell\not=p$). Let $k$ be a perfect field of characteristic $p>0$, $X$ be a smooth, separated and quasi-compact…

Algebraic Geometry · Mathematics 2011-10-25 Ahmed Abbes , Takeshi Saito

We give a simple characterization of the totally wild ramified valuations in a Galois extension of fields of characteristic p. This criterion involves the valuations of Artin-Schreier cosets of the F_{p^r}^\times-translation of a single…

Number Theory · Mathematics 2009-07-03 Lior Bary-Soroker , Elad Paran

Let K and F be complete discrete valuation fields of residue characteristic p>0. Let m be a positive integer no more than their absolute ramification indices. Let s and t be their uniformizers. Let L/K and E/F be finite extensions such that…

Number Theory · Mathematics 2019-02-20 Shin Hattori
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