Invariant subspaces for algebras of analytic operators associated with a periodic flow on a finite von Neumann algebra (Q1072069)

This paper discusses the invariant subspaces of the Hardy spaces \(H^{\infty}(a)\)-associated with a periodic flow on a von Neumann algebra. They are those subspaces \({\mathcal M}\) such as \(H^{\infty}(a){\mathcal M}\subseteq {\mathcal M}\). They are said to be pure if there exists no non-zero subspace \({\mathcal N}\subseteq {\mathcal M}\) such that \({\mathcal M}{\mathcal N}\subseteq {\mathcal N}\).