Published online by Cambridge University Press: 05 August 2014
To any positive contraction $Q$ on
$\ell ^{2}(W)$, there is associated a determinantal probability measure
$\mathbf{P}^{Q}$ on
$2^{W}$, where
$W$ is a denumerable set. Let
${\rm\Gamma}$ be a countable sofic finitely generated group and
$G=({\rm\Gamma},\mathsf{E})$ be a Cayley graph of
${\rm\Gamma}$. We show that if
$Q_{1}$ and
$Q_{2}$ are two
${\rm\Gamma}$-equivariant positive contractions on
$\ell ^{2}({\rm\Gamma})$ or on
$\ell ^{2}(\mathsf{E})$ with
$Q_{1}\leq Q_{2}$, then there exists a
${\rm\Gamma}$-invariant monotone coupling of the corresponding determinantal probability measures witnessing the stochastic domination
$\mathbf{P}^{Q_{1}}\preccurlyeq \mathbf{P}^{Q_{2}}$. In particular, this applies to the wired and free uniform spanning forests, which was known before only when
${\rm\Gamma}$ is residually amenable. In the case of spanning forests, we also give a second more explicit proof, which has the advantage of showing an explicit way to create the free uniform spanning forest as a limit over a sofic approximation. Another consequence of our main result is to prove that all determinantal probability measures
$\mathbf{P}^{Q}$ as above are
$\bar{d}$-limits of finitely dependent processes. Thus, when
${\rm\Gamma}$ is amenable,
$\mathbf{P}^{Q}$ is isomorphic to a Bernoulli shift, which was known before only when
${\rm\Gamma}$ is abelian. We also prove analogous results for sofic unimodular random rooted graphs.