Modifications of torsion-free coherent analytic sheaves

We study the transformation of torsion-free coherent analytic sheaves under proper modifications. More precisely, we study direct images of inverse image sheaves, and torsion-free preimages of direct image sheaves. Under some conditions, it is shown that torsion-free coherent sheaves can be realized as the direct image of locally free sheaves under modifications. Thus, it is possible to study coherent sheaves modulo torsion by reducing the problem to study vector bundles on manifolds. We apply this to reduced ideal sheaves and to the Grauert-Riemenschneider canonical sheaf of holomorphic n-forms.Comment: 28 pages; the article has been completely rewritten due to a wrong statement in the first versio

Perverse Sheaves on the Nilpotent Cone and Lusztig's Generalized Springer Correspondence

In this note, we consider perverse sheaves on the nilpotent cone. We prove orthogonality relations for the equivariant category of sheaves on the nilpotent cone in a method similar to Lusztig's for character sheaves. We also consider cleanness for cuspidal perverse sheaves and the generalized Lusztig--Shoji algorithm.Comment: 18 pages, minor typos correcte

Ind-Sheaves, distributions, and microlocalization

This is an announcement of a long paper in progress. On a locally compact space, we introduce the stack of ind-sheaves (ind-objects of the category of sheaves with compact support) and construct the analogous of the usual six operations on sheaves. As an application, we treat, in the formalism of ind-sheaves, functions with growth conditions such as the ``tempered holomorphic functions'' on a complex manifold. We also construct a microlocalization functor from the category of sheaves on a manifold to that of ind-sheaves on the cotangent bundle.Comment: 11 pages, Latex, uses package xypi