A comment on coposinormal operators

Abstract

Hyponormal operators are necessarily posinormal, but they need not be coposinormal. Coposinormality can nevertheless sometimes be an aid in determining hyponormality. This idea is applied to coposinormal factorable matrices whose interrupter is diagonal. Examples are given, including some Toeplitz matrices and some terraced matrices associated with the logistic sequence.

Keywords

• posinormal operator
• hyponormal operator
• factorable matrix
• terraced matrix
• Toeplitz matrix
• logistic sequence