Equivalences between isolated hypersurface singularities.
Equivariant virtual Betti numbers
We define a generalised Euler characteristic for arc-symmetric sets endowed with a group action. It coincides with the Poincaré series in equivariant homology for compact nonsingular sets, but is different in general. We put emphasis on the particular case of , and give an application to the study of the singularities of Nash function germs via an analog of the motivic zeta function of Denef and Loeser.
Ergänzung zur Arbeit "Quadratische Formen über affinen Algebren und ein algebraischer Beweis des Satzes von Borsuk-Ulam".
Espaces conormaux relatifs. I. Conditions de transversalité
Exotische Sphären als Umgebungsränder in speziellen komplexen Räumen.
Explicit birational geometry of threefolds of general type, I
Let be a complex nonsingular projective 3-fold of general type. We prove and for some positive integer . A direct consequence is the birationality of the pluricanonical map for all . Besides, the canonical volume has a universal lower bound .
Explicit resolutions of double point singularities of surfaces.
Locally analytically, any isolated double point occurs as a double cover of a smooth surface. It can be desingularized explicitly via the canonical resolution, as it is very well-known. In this paper we explicitly compute the fundamental cycle of both the canonical and minimal resolution of a double point singularity and we classify those for which the fundamental cycle differs from the fiber cycle. Moreover we compute the conditions that a double point singularity imposes to pluricanonical systems....
Extendability of differential forms on non-isolated singularities.
Families of Curves on Surfaces.
Families of smooth curves on surface singularities and wedges
Following the study of the arc structure of singularities, initiated by J. Nash, we give criteria for the existence of smooth curves on a surface singularity (S,O) and of smooth branches of its generic hypersurface section. The main applications are the following: the existence of a natural partition of the set of smooth curves on (S,O) into families, a description of each of them by means of chains of infinitely near points and their associated maximal cycle and the existence of smooth curves on...
Families of supersingular abelian surfaces
Fibre de Milnor d'un cône sur une courbe plane singulière.
Fibre de Milnor motivique à l’infini et composition avec un polynôme non dégénéré
Soit un corps de caractéristique nulle, un polynôme de Laurent en variables, à coefficients dans et non dégénéré pour son polyèdre de Newton à l’infini. Soit fonctions non constantes à variables séparées et définies sur des variétés lisses. A la manière de Guibert, Loeser et Merle, dans le cas local, nous calculons dans cet article, la fibre de Milnor motivique à l’infini de la composée en termes du polyèdre de Newton à l’infini de . Pour égal à la somme nous obtenons une formule...
Filtration par le poids et monodromie entière
Forme normale d'une fonction sur une surface de caractéristique positive
Fortsetzungsdefekte zweidimensionaler abelscher Quotienten-Singularitäten.
Generalized Newton-Puiseux Expansion and Abhyankar-Moh Semigroup Theorem.
Generalized polar varieties and an efficient real elimination
Let be a closed algebraic subvariety of the -dimensional projective space over the complex or real numbers and suppose that is non-empty and equidimensional. In this paper we generalize the classic notion of polar variety of associated with a given linear subvariety of the ambient space of . As particular instances of this new notion of generalized polar variety we reobtain the classic ones and two new types of polar varieties, called dual and (in case that is affine) conic. We show that...
Generische determinantielle Singularitäten: Homologische Eigenschaften des Derivationenmoduls.
Geometry of Puiseux expansions
We consider the space Curv of complex affine lines t ↦ (x,y) = (ϕ(t),ψ(t)) with monic polynomials ϕ, ψ of fixed degrees and a map Expan from Curv to a complex affine space Puis with dim Curv = dim Puis, which is defined by initial Puiseux coefficients of the Puiseux expansion of the curve at infinity. We present some unexpected relations between geometrical properties of the curves (ϕ,ψ) and singularities of the map Expan. For example, the curve (ϕ,ψ) has a cuspidal singularity iff it is a critical...