Specializations of Galois covers of the line

The main topic of the paper is the Hilbert-Grunwald property of Galois covers. It is a property that combines Hilbert's irreducibility theorem, the Grunwald problem and inverse Galois theory. We first present the main results of our preceding paper which concerned covers over number fields. Then we show how our method can be used to unify earlier works on specializations of covers over various fields like number fields, PAC fields or finite fields. Finally we consider the case of rational function fields kappa(x) and prove a full analog of the main theorem of our preceding paper.