Inflated G-Extensions for Algebraic Number Fields

Abstract

In 2018, Legrand and Paran proved a weaker form of the Inverse Galois Problem for all Hilbertian fields and all finite groups: that is, there exist possibly non-Galois extensions over given Hilbertian base field with given finite group as the group of field automorphisms fixing the base field. For $\mathbf Q$ it was proved earlier by M. Fried. In this paper our objective is to determine how big the degree of such extension can be compared to the order of the automorphism group. A special case of our result shows that if the Inverse Galois problem for $\bq$ has a solution for a finite group $G$, say of order $n$, then there exist algebraic number fields of degree $nm$, for any $m\ge3$ with the same automorphism group $G$.