Equivariant cohomology and sheaves

Sn-equivariant sheaves and Koszul cohomology

Background The Koszul cohomology of a line bundle L on an algebraic variety X was introduced by Green in [1]. Koszul cohomology is very closely related to the syzygies of the embedding defined by L (if L is very ample) and is thus related to a host of classical questions. We assume that the reader is already aware of these relations and the main theorems on Koszul cohomology; for a detailed dis...

Geometric Quantization and Equivariant Cohomology Geometric Quantization and Equivariant Cohomology

Sheaves and More Cohomology

of a Laurent series. If Op is the local ring of holomorphic functions around p. Take Mp the field of meromorphic functions around p, a principle part is just an element of the quotient groupMp/Op. The Mittag-Leffler question is, given a discrete set {pn} of points in S and a principle part at pn for each n, does there exist a meromorphic function f on S, holomorphic outside {pn}, whose principl...

Equivariant cohomology and equivariant intersection theory

This text is an introduction to equivariant cohomology, a classical tool for topological transformation groups, and to equivariant intersection theory, a much more recent topic initiated by D. Edidin and W. Graham. It is based on lectures given at Montréal is Summer 1997. Our main aim is to obtain explicit descriptions of cohomology or Chow rings of certain manifolds with group actions which ar...

Equivariant Cohomology and Resolution

The ‘Folk Theorem’ that a smooth action by a compact Lie group can be (canonically) resolved, by iterated blow up, to have unique isotropy type is proved in the context of manifolds with corners. This procedure is shown to capture the simultaneous resolution of all isotropy types in a ‘resolution tower’ which projects to a resolution, with iterated boundary fibration, of the quotient. Equivaria...