Videos

Glueing together copies of amenable groups

Presenter
December 8, 2016
Keywords:
  • sofic groups
  • higman group
  • amenability
  • a-T-menability
  • fixed point properties
  • group cohomology
  • Banach space
  • hyperbolic groups and generalizations
  • expander graph
  • index theory
  • non-commutative geometry
MSC:
  • 20F65
  • 11B37
  • 43A07
  • 19-xx
  • 20-xx
  • 43-xx
  • 46-xx
  • 57-xx
  • 58-xx
  • 43A07
  • 20J06
  • 46L80
Abstract
We suggest the beginning of a possible strategy towards finding a non-sofic group. In particular, we show that, if the Higman group were sofic, there would be a map from Z/pZ to itself, locally like an exponential map, satisfying a rather strong recurrence property. We also improve on existing bounds on the recurrence of exponential maps on Z/pZ. Our approach to (non)-soficity is based on the study of sofic representations of amenable subgroups of a sofic group.