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BEGIN:VEVENT
SUMMARY:Finite 2-complexes and 4-manifolds
DTSTART:20250613T141500
DTEND:20250613T154500
DTSTAMP:20260524T132334Z
UID:323d46481e06fad893c57da81f0d6c9118b6c42841f0b6fb96cdd3a3
CATEGORIES:Conferences - Seminars
DESCRIPTION:Ian Hambleton (McMaster University)\nFrom a finite 2-complex X
 \, one can construct a closed\, smooth 4-manifold M(X)\, for example as th
 e boundary of a thickened embedding in 5-dimensional Euclidean space. If X
  and Y have isomorphic fundamental groups\, then J H C Whitehead (1939) pr
 oved that X and Y become stably homotopy equivalent after adjoining some n
 umber of copies of the 2-sphere.\nThe talk will discuss the analogous 4-di
 mensional stable and unstable uniqueness question. We produce arbitrarily 
 large families of smooth 4-manifolds M(X)\, by varying X with a given fund
 amental group\, which are all stably diffeomorphic but pairwise distinct u
 p to homotopy.\nThis is joint work with John Nicholson (University of Glas
 gow).\n 
LOCATION:CM 1 517 https://plan.epfl.ch/?room==CM%201%20517 https://epfl.zo
 om.us/j/69833235472
STATUS:CONFIRMED
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