Jean-Claude Hausmann
(University of Geneva)
"Conjugation spaces"
Abstract:
There are classical examples of spaces X with an involution \tau whose mod 2-cohomology ring ressembles, as closely as possible, that of their fixed point set X^\tau: there is a ring isomorphism \kappa: H^{2*}(X)\isom{}H^*(X^\tau), halving the degree. Such examples include complex Grassmannians, toric manifolds, polygon spaces, etc.In this talk, we show that the ring isomorphism \kappa is part of an interesting structure in equivariant cohomology. Such spaces are called conjugation spaces and they enjoy remarkable properties. There are many examples, coming for instance from Lie groups and Hamiltonian geometry.