Hopf--Galois structures of cyclic type on parallel extensions of prime power degree

Fuente: arXiv
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Auteurs principaux: Darlington, Andrew, Tsang, Cindy
Format: Preprint
Publié: 2025
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author Darlington, Andrew
Tsang, Cindy
author_facet Darlington, Andrew
Tsang, Cindy
contents Let $L/K$ be any finite separable extension with normal closure $\widetilde{L}/K$. An extension $L'/K$ is said to be $\textit{parallel to $L/K$}$ if $L'$ is an intermediate field of $\widetilde{L}/K$ with $[L':K]=[L:K]$. We study the following question -- Given that $L/K$ admits a Hopf--Galois structure of type $N$, does it imply that every extension parallel to $L/K$ also admits a Hopf--Galois structure of type $N$? We completely solve this problem when the degree $[L:K]$ is a prime power and the type $N$ is cyclic. Our approach is group-theoretic and uses the work of Greither--Pareigis and Byott.
format Preprint
id arxiv_https___arxiv_org_abs_2510_14473
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Hopf--Galois structures of cyclic type on parallel extensions of prime power degree
Darlington, Andrew
Tsang, Cindy
Group Theory
Number Theory
Rings and Algebras
Let $L/K$ be any finite separable extension with normal closure $\widetilde{L}/K$. An extension $L'/K$ is said to be $\textit{parallel to $L/K$}$ if $L'$ is an intermediate field of $\widetilde{L}/K$ with $[L':K]=[L:K]$. We study the following question -- Given that $L/K$ admits a Hopf--Galois structure of type $N$, does it imply that every extension parallel to $L/K$ also admits a Hopf--Galois structure of type $N$? We completely solve this problem when the degree $[L:K]$ is a prime power and the type $N$ is cyclic. Our approach is group-theoretic and uses the work of Greither--Pareigis and Byott.
title Hopf--Galois structures of cyclic type on parallel extensions of prime power degree
topic Group Theory
Number Theory
Rings and Algebras
url https://arxiv.org/abs/2510.14473