$L_1$ Actions and Embeddings of Property A Spaces

Abstract

We provide several new characterizations of Property A for bounded degree graphs. In particular, we show that $(X,d)$ has Property A if and only if there is a proper gauge $\omega$ such that the Lipschitz free space $\mathrm{LF}(X,\omega \circ d)$ is isomorphic to ${\ell }_1$. As a consequence, all finitely generated groups with Property A admit proper uniformly Lipschitz affine actions on ${\ell }_1$. Moreover, for groups with finite Nagata dimension, we obtain actions with compression exponent 1. This result applies to higher rank lattices, such as $\mathrm{SL}(3,\mathbb{Z})$. We also show that a countable discrete group coarsely embeds into $L_1$ if and only if it admits a proper uniformly Lipschitz affine action on a subspace of $L_1$.

34 pages