MSI Colloquium

4pm Thursday 14 October 2004
Eugene Lerman
MSI

Contact group actions and stratified spaces

In the early 1990's Reyer Sjamaar and I proved that singular symplectic quotients are stratified spaces. That is, singular symplectic quotients naturally decompose into a locally finite union of manifolds and these manifolds fit together in a nice way. In particular intersection cohomology of such spaces makes sense. Unfortunately, since the links of singularities of singular symplectic quotients are not symplectic, our proof ended up being indirect.

More recently Chris Willett and I found a direct proof based on the fact that the links in question carry a contact structure.

This talk will not assume any familiarity with symplectic or contact geometry nor with stratified spaces.




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