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SUMMARY:Moduli spaces of reducible 3-manifolds - Jan Steinebrunner (Univer
 sity of Copenhagen)
DTSTART:20240605T091500Z
DTEND:20240605T100000Z
UID:TALK217447@talks.cam.ac.uk
DESCRIPTION:In joint work with Rachael Boyd and Corey Bregman we study the
  classifying space B Diff(M) of the diffeomorphism group of a connected\, 
 compact\, orientable 3-manifold M. By a theorem of Milnor every such M has
  a unique prime decomposition as a connected sum of prime 3-manifolds.\nTh
 e purpose of this talk is to explain how one can compute the moduli space 
 B Diff(M) in terms of the moduli spaces of prime factors. We build a contr
 actible space parametrising the systems of reducing spheres\, which yields
  a concrete model of B Diff(M).We use this to prove that if M has non-empt
 y boundary\, then B Diff(M rel boundary) has the homotopy type of a finite
  CW complex\, as was conjectured by Kontsevich.
LOCATION:External
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