Salle 2
  10 septembre 2019 à 09:30 
     We describe a method for counting the number of extensions of 
 with a given Galois group 
, founded upon the description of the absolute Galois group of 
 due to Jannsen and Wingberg. Because this description is only known for odd 
, our results do not apply to 
. We report on the results of counting such extensions for 
 of order up to 
 (except those divisible by 512), for 
, 5, 7, 11, 13. In particular, we highlight a relatively short list of minimal 
 that do not arise as Galois groups. Motivated by this list, we prove two theorems about the inverse Galois problem for 
: one giving a necessary condition for G to be realizable over 
 and the other giving a sufficient condition.