Le groupe de Witt d'une surface réelle.
Le spectre réel et la topologie des variétés algébriques sur un corps réel clos
Le topos étale réel d'un anneau
Lefschetz Fibrations and real Lefschetz fibrations
This note is based on the lectures that I have given during the winter school Winter Braids IV, School on algebraic and topological aspects of braid groups held in Dijon on 10 - 13 February 2014. The aim of series of three lectures was to give an overview of geometrical and topological properties of 4-dimensional Lefschetz fibrations. Meanwhile, I could briefly introduce real Lefschetz fibrations, fibrations which have certain symmetry, and could present some interesting features of them.This note...
Levels in algebra and topology.
Lie ideals and Jordan triple derivations in rings
Lipschitz stratification of real analytic sets
Lipschitz stratifications and Lipschitz isotopies
Local approximation of semialgebraic sets
Let be a closed semialgebraic subset of euclidean space of codimension at least one, and containing the origin as a non-isolated point. We prove that, for every real , there exists an algebraic set which approximates to order at . The special case generalizes the result of the authors that every semialgebraic cone of codimension at least one is the tangent cone of an algebraic set.
Local semianalytic geometry.