Problèmes de plongement finis sur les corps non commutatifs

Abstract

We extend finite embedding problems over fields, a central notion in inverse Galois theory, to the situation of a skew field $H$ of finite dimension over its center $h$. First, we show that solving a finite embedding problem over $H$ is equivalent to finding a solution to some finite embedding problem over $h$ fulfilling a polynomial constraint. Next, we show that every constant finite split embedding problem over the skew field of fractions $H(t)$ with central indeterminate $t$ has a solution, if $h$ is an ample field. This is a non-commutative analogue of a deep result of Pop. More generally, we solve such finite embedding problems over the skew field of fractions $H(t,\sigma )$ of the twisted polynomial ring $H[t,\sigma ]$, for some automorphisms $\sigma$ of $H$ of finite order. Our results extend previous works on the inverse Galois problem over skew fields.

in French