Linkage, Koszul Cohomology and Intersections

Abstract

In this chapter we apply the theory of linkage (i.e. liaison) or, more generally, that of residual intersections to the intersection cycle of a self-intersection, to embedded join and secant varieties, and to limit of join and secant varieties, especially in the case of low dimension or of small deviation. Once again, coning allows us to pass between the local and the geometrical cases.