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.