A remark on an integral structure of the imperfect coefficient ring of $(φ,Γ)$-modules

Fuente: arXiv
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Main Author: Watanabe, Takumi
Format: Preprint
Published: 2026
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author Watanabe, Takumi
author_facet Watanabe, Takumi
contents Let $K$ be a complete discrete valuation field of characteristic $0$ with perfect residue field of characteristic $p>0$. Let $\mathbb{A}_K$ denote the imperfect coefficient ring of $(φ,Γ)$-modules defined by Jean-Marc Fontaine. We prove that the canonical map $W(k_{K_\infty})[[μ]]\rightarrow \mathbb{A}_K\cap A_\mathrm{inf}$ is an isomorphism, even if $K$ is ramified. This fact was remarked by Nathalie Wach without proof.
format Preprint
id arxiv_https___arxiv_org_abs_2604_17559
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A remark on an integral structure of the imperfect coefficient ring of $(φ,Γ)$-modules
Watanabe, Takumi
Number Theory
Representation Theory
11S23
Let $K$ be a complete discrete valuation field of characteristic $0$ with perfect residue field of characteristic $p>0$. Let $\mathbb{A}_K$ denote the imperfect coefficient ring of $(φ,Γ)$-modules defined by Jean-Marc Fontaine. We prove that the canonical map $W(k_{K_\infty})[[μ]]\rightarrow \mathbb{A}_K\cap A_\mathrm{inf}$ is an isomorphism, even if $K$ is ramified. This fact was remarked by Nathalie Wach without proof.
title A remark on an integral structure of the imperfect coefficient ring of $(φ,Γ)$-modules
topic Number Theory
Representation Theory
11S23
url https://arxiv.org/abs/2604.17559