Subject: Re: another response
From: wziller@sas.upenn.edu
Date: Wed, 26 Apr 2006 12:44:55 -0400
A foollow up question:
In the same spirit,
what does one know if the action is only almost free,
i.e. the quotient is an orbifold.
I know there is something like orbifold cohomology (which I assume is
different
from equivariant cohomology).
Is there an orbifold Gysin sequence (if G=S3) which relates the ordinary
cohomology of the manifold with the obifold cohomology of the quotient
and an orbifold euler class?
and more generally a spectral sequence for orbifold cohomology?
I would like a reference where lots of examples are computed.
Can one describe invariants like the euler class in terms of the ordinary
cohomology of the manifold and the singular set (assuming it is smooth)
and the
orbifold group?
Wolfgang Ziller