The factorization of the derivative of Dickson polynomials.
The intersection of distinct Galois subrings is not necessarily Galois
The local lifting problem for actions of finite groups on curves
Let be an algebraically closed field of characteristic . We study obstructions to lifting to characteristic the faithful continuous action of a finite group on . To each such a theorem of Katz and Gabber associates an action of on a smooth projective curve over . We say that the KGB obstruction of vanishes if acts on a smooth projective curve in characteristic in such a way that and have the same genus for all subgroups . We determine for which the KGB obstruction...
The reflectiveness of covering morphisms in algebra and geometry.
Théorie de Galois pour une W*-Algèbre
Twisted forms of finite étale extensions and separable polynomials.