Calcolo del conduttore di curve algebriche e ideali di punti
For a smooth and proper curve over the fraction field of a discrete valuation ring , we explain (under very mild hypotheses) how to equip the de Rham cohomology with a canonical integral structure: i.e., an -lattice which is functorial in finite (generically étale) -morphisms of and which is preserved by the cup-product auto-duality on . Our construction of this lattice uses a certain class of normal proper models of and relative dualizing sheaves. We show that our lattice naturally...
We describe a new invariant for the action of the absolute Galois groups on the set of Grothendieck dessins. It uses the fact that the automorphism groups of regular dessins are isomorphic to automorphism groups of the corresponding Riemman surfaces and define linear represenatations of the space of holomorphic differentials. The characters of these representations give more precise information about the action of the Galois group than all previously known invariants, as it is shown by a series...
In this paper we characterize, in two different ways, the Newton polygons which are jacobian Newton polygons of a plane branch. These characterizations give in particular combinatorial criteria of irreducibility for complex series in two variables and necessary conditions which a complex curve has to satisfy in order to be the discriminant of a complex plane branch.