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SUMMARY:Arun Debray
DTSTART:20210301T200000Z
DTEND:20210301T210000Z
DTSTAMP:20260423T005722Z
UID:mitgt/10
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/mitgt/10/">S
 table diffeomorphism classification of some unorientable 4-manifolds</a>\n
 by Arun Debray as part of MIT Geometry and Topology Seminar\n\n\nAbstract\
 nKreck's modified surgery theory provides a bordism-theoretic classificati
 on of closed\, connected 4-manifolds up to stable diffeomorphism\, i.e. up
  to diffeomorphism after connect-sum with some number of copies of S^2 x S
 ^2. For some classes of unorientable 4-manifolds with fundamental group pi
 _1 finite of order 2 mod 4\, the classification question simplifies consid
 erably\, reducing to the case where pi_1 = Z/2. In this talk\, I'll explai
 n the generalities of Kreck's theorem and the ingredients that go into it\
 , then specialize and give the classification in the case where pi_1 is fi
 nite of order 2 mod 4. If time remains\, I'll discuss what changes when on
 e asks about the stable homeomorphism classification of topological 4-mani
 folds.\n
LOCATION:https://researchseminars.org/talk/mitgt/10/
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