On the Second Homology Group of the Discrete Group of Diffeomorphisms of the Circle
نویسنده
چکیده
Let G be the discrete group of orientation preserving diffeomorphisms of the circle, and let H be the subgroup of diffeomorphisms which are the identity in a neighborhood of a given point. It is proved that there is a short exact sequence in the integral homology of groups O-Hz(H)Hz(G) SZ-0. The epimorphism E can be identified with the Euler class for transversally foliated circle bundles. The sequence has a natural interpretation in terms of cobordism classes of foliated bundles with Euler class equal to 0.
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تاریخ انتشار 2001