Representing interpolated free group factors as group factors

Abstract

We construct a one parameter family of ICC groups $\{G_t{\}}_{t>1}$, with the property that the group factor $L(G_t)$ is isomorphic to the interpolated free group factor $L({\mathbb{F}}_t):=L({\mathbb{F}}_2{)}^{1/\sqrt{t-1}}$, for all $t$. Moreover, the groups $G_t$ have fixed cost $t$, are strongly treeable and freely generate any treeable ergodic equivalence relation of same cost.