A class of hyponormal operators and weak*-continuity of hermitian operators

TLDR: In this article, a class of *-hyponormal operators, called subnormal operators on a Hilbert space, were studied and a generalized Fuglede-Putnam theorem was proved for these operators.

Abstract: We will first in this paper consider a class of hyponormal operators which we call *-hyponormal operators. We give an example of a hyponormal operator which is not *-hyponormal. It follows from a theorem of Ackermans, van Eijndhoven and Martens [1] that subnormal operators on a Hilbert space are *-hyponormal. We prove a generalized Fuglede--Putnam theorem and some other results for these operators. We will also prove some results on the following problem which was mentioned in [4]: