Hopf-Galois Realizability of ${\mathbb{Z}}_n⋊{\mathbb{Z}}_2$

Abstract

Let $G$ and $N$ be finite groups of order $2n$ where $n$ is odd. We say the pair $(G,N)$ is Hopf-Galois realizable if $G$ is a regular subgroup of $\h(N)=N\rtimes\au(N)$. In this article we give necessary conditions on $G$ (similarly $N$) when $N$ (similarly $G$) is a group of the form ${\mathbb{Z}}_n⋊{\mathbb{Z}}_2$. Further we show that this condition is also sufficient if radical of $n$ is a Burnside number. This classifies all the skew braces which has the additive group (or the multiplicative group) to be isomorphic to ${\mathbb{Z}}_n⋊{\mathbb{Z}}_2$, in this case.