Videos

Discretization and Affine Approximation in High Dimensions

Presenter
October 17, 2011
Keywords:
  • Banach space
  • geometric group theory
  • differentiation theory
  • embedding theorems
  • reflexive spaces
  • Lipschitz continuity
  • affine geometry
MSC:
  • 58C20
  • 46-xx
  • 46Bxx
  • 46B20
  • 46B22
  • 54C25
  • 26A16
  • 46B85
Abstract
Bates, Johnson, Lindenstrauss, Preiss, and Schechtman proved that Lipschitz maps from the unit ball of a finite dimensional space into a superreflexive Banach space must be approximately affine on some smaller ball of a controlled radius r. However, one cannot read any kind of estimate of r from their proof. We present a new proof that gives a concrete lower bound for r. We also apply the affine approximation estimate to Bourgain’s discretization theorem and give a background to the related Ribe program. This is joint work with Assaf Naor.