English

On finite embedding problems with abelian kernels

Number Theory 2022-01-10 v2

Abstract

Given a Hilbertian field kk and a finite set S\mathcal{S} of Krull valuations of kk, we show that every finite split embedding problem GGal(L/k)G \rightarrow {\rm{Gal}}(L/k) over kk with abelian kernel has a solu\-tion Gal(F/k)G{\rm{Gal}}(F/k) \rightarrow G such that every vSv \in \mathcal{S} is totally split in F/LF/L. Two applications are then given. Firstly, we solve a non-constant variant of the Beckmann--Black problem for solvable groups: given a field kk and a non-trivial finite solvable group GG, every Galois field extension F/kF/k of group GG is shown to occur as the specialization at some t0kt_0 \in k of some Galois field extension E/k(T)E/k(T) of group GG with E⊈k(T)E \not \subseteq \overline{k}(T). Secondly, we contribute to inverse Galois theory over division rings, by showing that, for every division ring HH and every automorphism σ\sigma of HH of finite order, all finite semiabelian groups occur as Galois groups over the skew field of fractions H(T,σ)H(T, \sigma) of the twisted polynomial ring H[T,σ]H[T, \sigma].

Keywords

Cite

@article{arxiv.2112.12170,
  title  = {On finite embedding problems with abelian kernels},
  author = {François Legrand},
  journal= {arXiv preprint arXiv:2112.12170},
  year   = {2022}
}
R2 v1 2026-06-24T08:28:35.772Z