scholarly journals -neighborhoods and comparison theorems

2015 ◽  
Vol 151 (10) ◽  
pp. 1945-1964 ◽  
Author(s):  
Piotr Achinger
Keyword(s):  
Valuation Ring ◽  
Open Neighborhood ◽  
Residue Field ◽  
Discrete Valuation Ring ◽  
Universal Cover ◽  
Comparison Theorems ◽  
Main Ingredient ◽  
Generic Fiber ◽  
Mixed Characteristic ◽  
Original Approach

A technical ingredient in Faltings’ original approach to$p$-adic comparison theorems involves the construction of$K({\it\pi},1)$-neighborhoods for a smooth scheme$X$over a mixed characteristic discrete valuation ring with a perfect residue field: every point$x\in X$has an open neighborhood$U$whose generic fiber is a$K({\it\pi},1)$scheme (a notion analogous to having a contractible universal cover). We show how to extend this result to the logarithmically smooth case, which might help to simplify some proofs in$p$-adic Hodge theory. The main ingredient of the proof is a variant of a trick of Nagata used in his proof of the Noether normalization lemma.

scholarly journals Stabilité de l’holonomie sur les variétés quasi-projectives

2011 ◽  
Vol 147 (6) ◽  
pp. 1772-1792 ◽  
Author(s):  
Daniel Caro
Keyword(s):  
Valuation Ring ◽  
Residue Field ◽  
Discrete Valuation Ring ◽  
Mixed Characteristic ◽  
Complete Discrete Valuation Ring ◽  
The Stability

AbstractLet 𝒱 be a mixed characteristic complete discrete valuation ring with perfect residue field k. We solve Berthelot’s conjectures on the stability of the holonomicity over smooth projective formal 𝒱-schemes. Then we build a category of F-complexes of arithmetic 𝒟-modules over quasi-projective k-varieties with bounded and holonomic cohomology. We obtain its stability under Grothendieck’s six operations.

scholarly journals Good reduction of K3 surfaces

2017 ◽  
Vol 154 (1) ◽  
pp. 1-35 ◽  
Author(s):  
Christian Liedtke ◽  
Yuya Matsumoto
Keyword(s):  
Cohomology Group ◽  
Valuation Ring ◽  
Residue Field ◽  
Discrete Valuation Ring ◽  
Study Group ◽  
K3 Surface ◽  
Good Reduction ◽  
Mixed Characteristic ◽  
Galois Action ◽  
Stable Reduction

Let $K$ be the field of fractions of a local Henselian discrete valuation ring ${\mathcal{O}}_{K}$ of characteristic zero with perfect residue field $k$. Assuming potential semi-stable reduction, we show that an unramified Galois action on the second $\ell$-adic cohomology group of a K3 surface over $K$ implies that the surface has good reduction after a finite and unramified extension. We give examples where this unramified extension is really needed. Moreover, we give applications to good reduction after tame extensions and Kuga–Satake Abelian varieties. On our way, we settle existence and termination of certain flops in mixed characteristic, and study group actions and their quotients on models of varieties.

scholarly journals On the lifting of the Dade group

2019 ◽  
Vol 22 (3) ◽  
pp. 441-451
Author(s):  
Caroline Lassueur ◽  
Jacques Thévenaz
Keyword(s):  
Valuation Ring ◽  
Residue Field ◽  
Discrete Valuation Ring ◽  
Group Homomorphism ◽  
Complete Discrete Valuation Ring ◽  
Dade Group

Abstract For the group of endo-permutation modules of a finite p-group, there is a surjective reduction homomorphism from a complete discrete valuation ring of characteristic 0 to its residue field of characteristic p. We prove that this reduction map always has a section which is a group homomorphism.

scholarly journals Arithmetic 𝒟-modules on the unit disk. With an appendix by Shigeki Matsuda

2011 ◽  
Vol 148 (1) ◽  
pp. 227-268 ◽  
Author(s):  
Richard Crew
Keyword(s):  
Unit Disk ◽  
Valuation Ring ◽  
Discrete Valuation Ring ◽  
Mixed Characteristic ◽  
Complete Discrete Valuation Ring ◽  
Canonical Extensions

AbstractLet 𝒱 be a complete discrete valuation ring of mixed characteristic. We classify arithmetic 𝒟-modules on Spf(𝒱[[t]]) up to certain kind of ‘analytic isomorphism’. This result is used to construct canonical extensions (in the sense of Katz and Gabber) for objects of this category.

Extending Endo-monomial Modules

2013 ◽  
Vol 20 (01) ◽  
pp. 169-172
Author(s):  
Ziqun Lu ◽  
Jiping Zhang
Keyword(s):  
Finite Group ◽  
Valuation Ring ◽  
Residue Field ◽  
Discrete Valuation Ring ◽  
Characteristic P ◽  
Complete Discrete Valuation Ring ◽  
A Finite Group

Let G be a finite group with a normal Sylow p-subgroup P. Let [Formula: see text] be a complete discrete valuation ring with residue field F of characteristic p. Let M be an indecomposable endo-monomial [Formula: see text]-module. In this paper we prove that M extends to an [Formula: see text]-module if and only if M is G-stable. A similar and well-known version for endo-permutation modules is due to Dade.

scholarly journals MODELS OF TORSORS AND THE FUNDAMENTAL GROUP SCHEME

2016 ◽  
Vol 230 ◽  
pp. 18-34 ◽  
Author(s):  
MARCO ANTEI ◽  
MICHEL EMSALEM
Keyword(s):  
Finite Number ◽  
Fundamental Group ◽  
Galois Group ◽  
Closed Subset ◽  
Valuation Ring ◽  
Group Scheme ◽  
Discrete Valuation Ring ◽  
Generic Fiber ◽  
Natural Morphism ◽  
Tannakian Category

Given a relative faithfully flat pointed scheme over the spectrum of a discrete valuation ring $X\rightarrow S$, this paper is motivated by the study of the natural morphism from the fundamental group scheme of the generic fiber $X_{\unicode[STIX]{x1D702}}$ to the generic fiber of the fundamental group scheme of $X$. Given a torsor $T\rightarrow X_{\unicode[STIX]{x1D702}}$ under an affine group scheme $G$ over the generic fiber of $X$, we address the question of finding a model of this torsor over $X$, focusing in particular on the case where $G$ is finite. We provide several answers to this question, showing for instance that, when $X$ is integral and regular of relative dimension 1, such a model exists on some model $X^{\prime }$ of $X_{\unicode[STIX]{x1D702}}$ obtained by performing a finite number of Néron blowups along a closed subset of the special fiber of $X$. Furthermore, we show that when $G$ is étale, then we can find a model of $T\rightarrow X_{\unicode[STIX]{x1D702}}$ under the action of some smooth group scheme. In the first part of the paper, we show that the relative fundamental group scheme of $X$ has an interpretation as the Tannaka Galois group of a Tannakian category constructed starting from the universal torsor.

scholarly journals The First Monsky-Washnitzer Cohomology Group

1972 ◽  
Vol 48 ◽  
pp. 99-128
Author(s):  
David Meredith
Keyword(s):  
Finite Type ◽  
Characteristic Zero ◽  
Cohomology Group ◽  
Valuation Ring ◽  
Residue Field ◽  
Discrete Valuation Ring ◽  
Perfect Field ◽  
Quotient Field ◽  
Complete Discrete Valuation Ring

Throughout this paper, k is a perfect field of characteristic p > 0, R is a complete discrete valuation ring with residue field k and quotient field of characteristic zero, and Z is a connected smooth prescheme of finite type over k.

FINITE POSETS AND THEIR REPRESENTATION ALGEBRAS

2010 ◽  
Vol 20 (01) ◽  
pp. 27-38 ◽  
Author(s):  
MURRAY GERSTENHABER ◽  
MARY SCHAPS
Keyword(s):  
Valuation Ring ◽  
Residue Field ◽  
Discrete Valuation Ring ◽  
Dimensional Algebra ◽  
Finite Poset ◽  
Finite Dimensional ◽  
Triangular Representation ◽  
Complete Discrete Valuation Ring ◽  
Characteristic 2 ◽  
Finite Posets

A finite poset (P ≼ S) determines a finite dimensional algebra TP over the field 𝔽 of two elements, with an upper triangular representation. We determine the structure of the radical of the representation algebra A of the monoid (TP,·) over a field of characteristic different from 2. We also consider degenerations of A over a complete discrete valuation ring with residue field of characteristic 2.

Polynomials inducing the zero function on chain rings

2018 ◽  
Vol 17 (08) ◽  
pp. 1850160 ◽  
Author(s):  
Mark W. Rogers ◽  
Cameron Wickham
Keyword(s):  
Maximal Ideal ◽  
Principal Ideal ◽  
Valuation Ring ◽  
Residue Field ◽  
Discrete Valuation Ring ◽  
Minimal Set ◽  
Principal Ideal Ring ◽  
Ideal Formula ◽  
Zero Function ◽  
The Ideal

We provide a minimal set of generators for the ideal of polynomials in [Formula: see text] that map the maximal ideal [Formula: see text] into one of its powers [Formula: see text], where [Formula: see text] is a discrete valuation ring with a finite residue field. We use this to provide a minimal set of generators for the ideal of polynomials in [Formula: see text] that send [Formula: see text] to zero, where [Formula: see text] is a finite commutative local principal ideal ring.

Integer-valued skew polynomials

2020 ◽  
pp. 2150114
Author(s):  
Nicholas J. Werner
Keyword(s):  
Valuation Ring ◽  
Integral Domain ◽  
Residue Field ◽  
Discrete Valuation Ring ◽  
Ring Structure ◽  
Polynomial Rings ◽  
Skew Polynomial Ring ◽  
Skew Polynomials ◽  
Skew Polynomial Rings ◽  
Skew Polynomial

For a commutative integral domain [Formula: see text] with field of fractions [Formula: see text], the ring of integer-valued polynomials on [Formula: see text] is [Formula: see text]. In this paper, we extend this construction to skew polynomial rings. Given an automorphism [Formula: see text] of [Formula: see text], the skew polynomial ring [Formula: see text] consists of polynomials with coefficients from [Formula: see text], and with multiplication given by [Formula: see text] for all [Formula: see text]. We define [Formula: see text], which is the set of integer-valued skew polynomials on [Formula: see text]. When [Formula: see text] is not the identity, [Formula: see text] is noncommutative and evaluation behaves differently than it does for ordinary polynomials. Nevertheless, we are able to prove that [Formula: see text] has a ring structure in many cases. We show how to produce elements of [Formula: see text] and investigate its properties regarding localization and Noetherian conditions. Particular attention is paid to the case where [Formula: see text] is a discrete valuation ring with finite residue field.

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