A remark on the ultrapower algebra of the hyperfinite factor

Ionut Chifan, Sayan Das

On page 43 in \cite{Po83} Sorin Popa asked whether the following property holds: \emph{If $\omega$ is a free ultrafilter on $\mathbb{N}$ and ${\mathcal{R}}_1\subseteq \mathcal{R}$ is an irre…