BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Homotopy equivalence and simple homotopy equivalence of manifolds 
 - Csaba Nagy (University of Glasgow)
DTSTART:20240617T124500Z
DTEND:20240617T131500Z
UID:TALK217372@talks.cam.ac.uk
DESCRIPTION:A homotopy equivalence between finite CW-complexes is called s
 imple if it is homotopic to a composition of elementary collapses and expa
 nsions. Lens spaces provide famous examples of manifolds that are homotopy
  equivalent but not simple homotopy equivalent to each other\, in all $\\g
 eq 3$ odd dimensions. However\, no even-dimensional examples are known in 
 the literature.\nWe construct even-dimensional manifolds that are homotopy
  equivalent (in fact h-cobordant) but not simple homotopy equivalent to ea
 ch other. More generally\, we give a purely algebraic characterisation of 
 groups G with the property that there exists a pair of manifolds with fund
 amental group G that are h-cobordant but not simple homotopy equivalent.\n
 This is joint work with Johnny Nicholson and Mark Powell.
LOCATION:External
END:VEVENT
END:VCALENDAR