On CSM classes via Chern-Fulton classes of f-schemes (1501.03864v3)

Abstract: The Chern-Fulton class is a generalization of Chern class to the realm of arbitrary embeddable schemes. While Chern-Fulton classes are sensitive to non-reduced scheme structure, they are not sensitive to possible singularities of the underlying support, thus at first glance are not interesting from a singularity theory viewpoint. However, we introduce a class of formal objects which we think of as `fractional schemes', or f-schemes for short, and then show that when one broadens the domain of Chern-Fulton classes to f-schemes one may indeed recover singularity invariants of varieties and schemes. More precisely, we show that for almost all global complete intersections, their Chern-Schwartz-Macpherson classes may be computed via Chern-Fulton classes of f-schemes.