A propagation property of free entropy dimension

Abstract

Let M be a tracial von Neumann algebra and A be a weakly dense unital C*-subalgebra of M. We say that a set X is a W*-generating set for M if the von Neumann algebra generated by X is M and that X is a C*-generating set for A if the unital C*-algebra generated by X is A. For any finite W*-generating set X for M we show that $\delta_0(X) \leq sup {\delta_0(Y): Y is a finite C*-generating set for A}$ where $\delta_0$ denotes the microstates free entropy dimension. It follows that if $sup {\delta_0(Y): Y is a finite C*-generating set for C*_{red}(\mathbb F_2)} < \infty$, then the free group factors are all nonisomorphic.