Lipschitz stratification of real analytic sets
L’objectif dans ce travail est de présenter une généralisation pour l’obstruction d’Euler locale d’une fonction holomorphe singulière à l’origine dans le cas d’une application holomorphe , où est un germe de variété analytique complexe, équidimensionnel de dimension . Le résultat principal (Théorème 6.1) exprime l’obstruction d’Euler locale, définie pour un -repère par Brasselet, Seade, Suwa, en fonction de l’obstruction d’Euler relative à .
For a stratified mapping , we consider the condition concerning the kernel of the differential of . We show that the condition is equivalent to the condition which has a more obvious geometric content.
We study the topological invariant ϕ of Kwieciński and Tworzewski, particularly beyond the case of mappings with smooth targets. We derive a lower bound for ϕ of a general mapping, which is similarly effective as the upper bound given by Kwieciński and Tworzewski. Some classes of mappings are identified for which the exact value of ϕ can be computed. Also, we prove that the variation of ϕ on the source space of a mapping with a smooth target is semicontinuous in the Zariski topology.
Let F be a codimension one holomorphic foliation whose singular set Σ is contained in a compact leaf S of F.When F is of dimension one, Σ is a set of isolated points {q1, ..., qr}, C. Camacho and P. Sad define the index of F at each point qk and prove that the sum of these indices equals the Euler class c1(E) of the fibre bundle E normal to S.Generally, whenever Σ is of any dimension m, we can define a such index iα along the maximal dimension strates {Σα} of a suitable stratification of the complex...