English

Unramified extensions over low degree number fields

Number Theory 2019-01-15 v1

Abstract

For various nonsolvable groups GG, we prove the existence of extensions of the rationals Q\mathbb{Q} with Galois group GG and inertia groups of order dividing ge(G)ge(G), where ge(G)ge(G) is the smallest exponent of a generating set for GG. For these groups GG, this gives the existence of number fields of degree ge(G)ge(G) with an unramified GG-extension. The existence of such extensions over Q\mathbb{Q} for all finite groups would imply that, for every finite group GG, there exists a quadratic number field admitting an unramified GG-extension, as was recently conjectured. We also provide further evidence for the existence of such extensions for all finite groups, by proving their existence when Q\mathbb{Q} is replaced with a function field k(t)k(t) where kk is an ample field.

Keywords

Cite

@article{arxiv.1901.03985,
  title  = {Unramified extensions over low degree number fields},
  author = {Joachim König and Danny Neftin and Jack Sonn},
  journal= {arXiv preprint arXiv:1901.03985},
  year   = {2019}
}
R2 v1 2026-06-23T07:10:04.460Z