English

Hopf Galois module structure of dihedral degree $2p$ extensions of $\mathbb{Q}_p$

Number Theory 2021-05-26 v2

Abstract

Let pp be an odd prime. For field extensions L/QpL/\mathbb{Q}_p with Galois group isomorphic to the dihedral group D2pD_{2p} of order 2p2p, we consider the problem of computing a basis of the associated order in each Hopf Galois structure and the module structure of the ring of integers OL\mathcal{O}_L. We solve the case in which L/QpL/\mathbb{Q}_p is not totally ramified and present a practical method which provides a complete answer for the cases p=3p=3 and p=5p=5. We see that within this family of dihedral extensions, the ring of integers is always free over the associated orders in the different Hopf Galois structures.

Keywords

Cite

@article{arxiv.2011.05024,
  title  = {Hopf Galois module structure of dihedral degree $2p$ extensions of $\mathbb{Q}_p$},
  author = {Daniel Gil-Muñoz and Anna Rio},
  journal= {arXiv preprint arXiv:2011.05024},
  year   = {2021}
}

Comments

The paper has been updated with a slightly different structure. We have fixed some mistakes and obtained different answers to the same questions