English

Specialization results and ramification conditions

Number Theory 2015-03-17 v6

Abstract

Given a hilbertian field kk of characteristic zero and a finite Galois extension E/k(T)E/k(T) with group GG such that E/kE/k is regular, we produce some specializations of E/k(T)E/k(T) at points t0P1(k)t_0 \in \mathbb{P}^1(k) which have the same Galois group but also specified inertia groups at finitely many given primes. This result has two main applications. Firstly we conjoin it with previous works to obtain Galois extensions of Q\mathbb{Q} of various finite groups with specified local behavior - ramified or unramified - at finitely many given primes. Secondly, in the case kk is a number field, we provide criteria for the extension E/k(T)E/k(T) to satisfy this property: at least one Galois extension F/kF/k of group GG is not a specialization of E/k(T)E/k(T).

Keywords

Cite

@article{arxiv.1310.2189,
  title  = {Specialization results and ramification conditions},
  author = {François Legrand},
  journal= {arXiv preprint arXiv:1310.2189},
  year   = {2015}
}
R2 v1 2026-06-22T01:42:39.698Z