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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/6715

Title: The numerical range of linear operators
Authors: Mecheri, Salah
Keywords: Numerical range
Paranormal operators
Convexoid operators
Issue Date: 1991
Publisher: Mathematics Subject Classification
Abstract: In [27] J.P.Williams showed that an operator A E B(H) is normaloid if and only if it is convexoid. It is known that the part if in J.P.William’s result is not true as it mentioned in the review MR0264445. In this paper we will present an example which contractics the part “ if ” in J.P. williams’ result. We also give a simple proof of the part “only if” of this result. A necessary and sufficient condition for an operator A E B(H) to be convexoid is also given.
Description: Department of mathematics King saud university, college of science P.o.box 2455, Riyadh 11451, Saudi arabia
URI: http://hdl.handle.net/123456789/6715
Appears in Collections:The Excelent Center of Science & Mathematic Education

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