Seminari di Sistemi Dinamici Olomorfi 2017-2018
timetable:
Tue 22 May, 14:00 - 15:00, Sala Conferenze Centro De Giorgi
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seminar: On the bounded cohomology of actions of multidimensional groups
speaker: Jon Aaronson (Tel Aviv University)abstract: Although each cocycle for a action of the integers is specified by the sequence of Birkhoff sums of a function, it is relatively difficult to specify cocycles for the actions of multidimensional groups such as Z2.
We'll see that if (X,T) is a transitive action of the finitely generated (countable) group G by homeomorphism of the polish space X, and B is a separable Banach space, there is a cocycle F:G x X --> B with each x
--> F(g,x) bounded and uniformly continuous so that the skew product action (X x B,S) is transitive where Sg(x,b)=(Tgx,b+F(g,x)).
This result was shown for transitive actions of the integers by E.A. Sidorov in 1973.
This is joint work with Benjamin Weiss: arXiv:1712.05196
timetable:
Tue 22 May, 14:00 - 15:00, Sala Conferenze Centro De Giorgi
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