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Generators for Gelfand-Fuchs cohomology on surfacesGeometry/Topology
|Speaker: ||Friedrich Wagemann, University of Nantes|
|Location: ||2112 MSB|
|Start time: ||Tue, Mar 19 2013, 3:10PM|
In 1968-70, Israel Gelfand and Dimitri Fuchs did pioneering work on the
cohomology of the Lie algebra of smooth vector fields on manifolds,
nowadays known as Gelfand-Fuchs cohomology. The dimensions of the
corresponding cohomology spaces for a given manifold M of dimension n can
be computed in principle from the cohomology H(Wn) of the Lie algebra
of formal vector fields in n variables for which a basis (Vey basis) is known. There exists a manifold Xn whose singular cohomology is isomorphic to H(Wn). For manifolds M with vanishing Pontryagin classes, Gelfand-Fuchs cohomology is then isomorphic to the singular cohomology of Map(M,Xn) (Theorem of Haefliger 1974, Bott-Segal 1977). For n=1, X1=S3 (the standard 3-sphere) and well-known explicit generators of the cohomology spaces are available. For n>1, this is (to our knowledge) not the case.
We will review Gelfand-Fuchs cohomology along these lines and then come to our recent computations for some generators of the Gelfand-Fuchs cohomology spaces for surfaces (i.e. n=2).
There will be a dinner for the speaker.