Unramified extensions over low degree number fields

Joachim König, Danny Neftin, Jack Sonn

Research output: Contribution to journalArticlepeer-review

Abstract

For various nonsolvable groups G, we prove the existence of extensions of the rationals Q with Galois group G and inertia groups of order dividing ge(G), where ge(G) is the smallest exponent of a generating set for G. For these groups G, this gives the existence of number fields of degree ge(G) with an unramified G-extension. The existence of such extensions over Q for all finite groups would imply that, for every finite group G, there exists a quadratic number field admitting an unramified G-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 is replaced with a function field k(t) where k is an ample field.

Original languageEnglish
Pages (from-to)72-87
Number of pages16
JournalJournal of Number Theory
Volume212
DOIs
StatePublished - Jul 2020

Keywords

  • Bounded ramification
  • Galois theory
  • Specialization of Galois covers
  • Unramified extensions

All Science Journal Classification (ASJC) codes

  • Algebra and Number Theory

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