Nilpotents, Integral Closure and Equisingularity conditions

Abstract

In earlier work, the author described various stratification conditions for a complex analytic set X in terms of the theory of integral closure of modules. However, even if an analytic set has a reduced structure, often geometric operations like intersection give a non-reduced structure on the resulting analytic space. In this note we show that it is not necessary for X to have a reduced structure to apply the earlier integral closure results. As an application we give a simple proof of a necessary and sufficient condition for the Whitney conditions to pass to the intersection of X with a hyperplane containing the smooth stratum Y, and for this intersection to be "typical". In the case where X is a family of ICIS singularities, we show the condition on H at a point y of Y depends only on the fiber of the family over y.