Optimal factor matchings for point processes on non-amenable unimodular graphs

Abstract

Consider a unit-intensity point process $\hat{I}$ on the vertex set $V$ of a transitive non-amenable unimodular graph. We study invariant matchings between $\hat{I}$ and $V$ having small typical matching distances. When $\hat{I}$ is either a Poisson process or i.i.d. perturbations of the vertex set, we determine the optimal matching distance and show that it can be attained by a factor matching scheme (that is, a deterministic and equivariant function of $\hat{I}$).

19 pages