Stiefel-Whitney Classes and the Conormal Cycle of a Singular Variety

摘要

A geometric construction of Sullivan's Stiefel-Whitney homology classes of areal analytic variety $X$ is given by means of the conormal cycle of anembedding of $X$ in a smooth variety. We prove that the Stiefel-Whitney classesdefine additive natural transformations from certain constructible functions tohomology. We also show that, for a complex analytic variety, these classes arethe mod 2 reductions of the Chern-MacPherson classes.