We extend von Neumann’s Double Commutant Theorem to the setting of nonselfadjoint operator algebras A, while restricting the notion of commutants of a subset S of A to those operators in A which commute with every operator in S. If A is a completely distributive commutative subspace lattice algebra acting on a Hilbert space H, we obtain an alternate characterization (to those of Erdos–Power and...

we study topological von neumann regularity and principal von neumann regularity of banach algebras. our main objective is comparing these two types of banach algebras and some other known banach algebras with one another. in particular, we show that the class of topologically von neumann regular banach algebras contains all $c^*$-algebras, group algebras of compact abelian groups and cer...