Open Access Research

An elementary operator and generalized Weyl’s theorem

Fugen Gao* and Xiaochun Li

Author Affiliations

College of Mathematics and Information Science, Henan Normal University, Xinxiang, Henan, 453007, China

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Journal of Inequalities and Applications 2012, 2012:243 doi:10.1186/1029-242X-2012-243

Published: 24 October 2012

Abstract

A Hilbert space operator T belongs to class A if <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M1','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M1">View MathML</a>. Let <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M2','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M2">View MathML</a> denote either <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M3','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M3">View MathML</a> or <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M4','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M4">View MathML</a>, where <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M3','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M3">View MathML</a> and <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M4','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M4">View MathML</a> denote the generalized derivation and the elementary operator on a Banach space <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M7','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M7">View MathML</a> defined by <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M8','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M8">View MathML</a> and <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M9','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M9">View MathML</a> respectively. If A and <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M10','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M10">View MathML</a> are class A operators, we show that <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M2','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M2">View MathML</a> is polaroid and generalized Weyl’s theorem holds for <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M12','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M12">View MathML</a>, generalized a-Weyl’s theorem holds for <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M13','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M13">View MathML</a> for every <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M14','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M14">View MathML</a> and f is not constant on each connected component of the open set U containing <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M15','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M15">View MathML</a>, where <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M16','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M16">View MathML</a> denotes the set of all analytic functions in a neighborhood of <a onClick="popup('http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M17','MathML',630,470);return false;" target="_blank" href="http://www.journalofinequalitiesandapplications.com/content/2012/1/243/mathml/M17">View MathML</a>.

MSC: 47B20, 47A63.

Keywords:
class A operators; generalized derivation; elementary operator; generalized Weyl’s theorem; generalized a-Weyl’s theorem