Salah Mecheri

Department of Mathematics. College of Science. King Saud University. P.O.Box 2455, Riyadh 11451. Saudi Arabia

e-mail: mecherisalah@hotmail.com

Abstract. In this paper we will investigate the normality in (WN) and (Y) classes.

Keywords and phrases. Normal operators, Hilbert space, hermitian operators.

2000 Mathematics Subject Classification. Primary: 47A15. Secondary: 47B20, 47A63.

Resumen. En este artículo nosotros investigaremos la normalidad en clases (WN) y (Y).

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(Recibido en mayo de 2005. Aceptado en septiembre de 2005)