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arXiv · 1805.10830

Non-existence of Hopf-Galois structures and bijective crossed homomorphisms

Cindy Tsang
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Abstract

By work of C. Greither and B. Pareigis as well as N. P. Byott, the enumeration of Hopf-Galois structures on a Galois extension of fields with Galois group $G$ may be reduced to that of regular subgroups of $\mbox{Hol}(N)$ isomorphic to $G$ as $N$ ranges over all groups of order $|G|$, where $\mbox{Hol}(-)$ denotes the holomorph. In this paper, we shall give a description of such subgroups of $\mbox{Hol}(N)$ in terms of bijective crossed homomorphisms $G\longrightarrow N$, and then use it to study two questions related to non-existence of Hopf-Galois structures.

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Cindy Tsang. 2018-05-28. Non-existence of Hopf-Galois structures and bijective crossed homomorphisms. https://doi.org/10.1016/j.jpaa.2018.09.016

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