Problème inverse de Galois : critère de rigidité
In this master thesis we study finite Galois extensions of C(x). We prove  Riemann existence theorem. The notions of rigidity, weak rigidity, and rationality are developed. We obtain the rigidity criterion which enable us to realise some groups as Galois groups over Q. Many examples of ramification types are constructed.
Type de ramification Ramification type Galois covering Kappa-rational tuple of conjugacy classes