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SUMMARY:An exotic Dehn twist after two stabilizations - Sungkyung Kang (Ca
 mbridge)
DTSTART:20251022T150000Z
DTEND:20251022T160000Z
UID:TALK238366@talks.cam.ac.uk
CONTACT:Oscar Randal-Williams
DESCRIPTION:Unlike in higher dimensions\, most exotic phenomena on simply-
 connected 4-manifolds are unstable\; they become non-exotic after finitely
  many stabilizations. While we now know that some of them survive one stab
 ilization\, nothing is known about their behavior when we stabilize them m
 ore than once. In this talk\, we present the first example of an exotic di
 ffeomorphism on a smooth contractible 4-manifold\, given as a boundary Deh
 n twist along its (nontrivial) boundary\, which stays exotic after two sta
 bilizations. This is an ongoing joint work with JungHwan Park and Masaki T
 aniguchi.
LOCATION:MR13
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