Positive projections of von Neumann algebras onto \(JW\)-algebras
Let \(N\) be a von Neumann algebra. We consider faithful normal positive linear idempotant unital maps from \(N\) into itself. The range of such a map is a Jordan algebra \(A\). We show the existence and structure theorems for such maps and for conditional expectations of \(N\) onto the von Neumann algebra generated by \(A\).
scientific article; zbMATH DE number 1087279
scientific article