Ein Homomorphiesatz und verwandte Operatoren in topologischen Vektorräumen.
Elements of C*-algebras commuting with their Moore-Penrose inverse
We give new necessary and sufficient conditions for an element of a C*-algebra to commute with its Moore-Penrose inverse. We then study conditions which ensure that this property is preserved under multiplication. As a special case of our results we recover a recent theorem of Hartwig and Katz on EP matrices.
Erratum to: “Towards a theory of some unbounded linear operators on -adic Hilbert spaces and applications”
Every Frame is a Sum of Three (But Not Two) Orthonormal Bases-and Other Frame Representations.
Exponentials of normal operators and commutativity of operators: a new approach
We present a new approach to the question of when the commutativity of operator exponentials implies that of the operators. This is proved in the setting of bounded normal operators on a complex Hilbert space. The proofs are based on some results on similarities by Berberian and Embry as well as the celebrated Fuglede theorem.