Hopf Galois extensions of Hopf algebroids

Fuente: arXiv
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Auteurs principaux: Han, Xiao, Schauenburg, Peter
Format: Preprint
Publié: 2024
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author Han, Xiao
Schauenburg, Peter
author_facet Han, Xiao
Schauenburg, Peter
contents We study Hopf Galois extensions of Hopf algebroids as a generalization of the theory for Hopf algebras. More precisely, we introduce (skew-)regular comodules and generalize the structure theorem for relative Hopf modules. Also, we show that if $N\subseteq P$ is a left $\mathcal{L}$-Galois extension and $Γ$ is a 2-cocycle of $\mathcal{L}$, then for the twisted comodule algebra ${}_ΓP$, $N\subseteq{}_ΓP$ is a left Hopf Galois extension of the twisted Hopf algebroid $\mathcal{L}^Γ$. We study twisted Drinfeld doubles of Hopf algebroids as examples for the Drinfeld twist theory. Finally, we introduce cleft extension and $σ$-twisted crossed products of Hopf algebroids. Moreover, we show the equivalence of cleft extensions, $σ$-twisted crossed products, and Hopf Galois extensions with normal basis properties, which generalize the theory of cleft extensions of Hopf algebras.
format Preprint
id arxiv_https___arxiv_org_abs_2406_11058
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Hopf Galois extensions of Hopf algebroids
Han, Xiao
Schauenburg, Peter
Quantum Algebra
We study Hopf Galois extensions of Hopf algebroids as a generalization of the theory for Hopf algebras. More precisely, we introduce (skew-)regular comodules and generalize the structure theorem for relative Hopf modules. Also, we show that if $N\subseteq P$ is a left $\mathcal{L}$-Galois extension and $Γ$ is a 2-cocycle of $\mathcal{L}$, then for the twisted comodule algebra ${}_ΓP$, $N\subseteq{}_ΓP$ is a left Hopf Galois extension of the twisted Hopf algebroid $\mathcal{L}^Γ$. We study twisted Drinfeld doubles of Hopf algebroids as examples for the Drinfeld twist theory. Finally, we introduce cleft extension and $σ$-twisted crossed products of Hopf algebroids. Moreover, we show the equivalence of cleft extensions, $σ$-twisted crossed products, and Hopf Galois extensions with normal basis properties, which generalize the theory of cleft extensions of Hopf algebras.
title Hopf Galois extensions of Hopf algebroids
topic Quantum Algebra
url https://arxiv.org/abs/2406.11058