Groups with the Haagerup Property: Gromov's A-T-Menability (Softcover Reprint of the Original 1st 2001)Paperback - Softcover Reprint of the Original 1st 2001, 1 November 2012

A locally compact group has the Haagerup property, or is a-T-menable in the sense of Gromov, if it admits a proper isometric action on some affine Hilbert space. As Gromov's pun is trying to indicate, this definition is designed as a strong negation to Kazhdan's property (T), characterized by the fact that every isometric action on some affine Hilbert space has a fixed point. This book is to covers various aspects of the Haagerup property. It gives several new examples.