Measures of noncompactness and essential pseudospectra on Banach space |
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| Authors: | Aymen Ammar Aref Jeribi |
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| Affiliation: | Département de Mathématiques, Université de Sfax, Faculté des sciences de Sfax, , 3000 Sfax, Tunisia |
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| Abstract: | In this research article, we work with the notion of the measures of noncompactness in order to establish some results concerning the essential pseudospectra of closed, densely defined linear operators in the Banach space. We start by giving a refinement of the definition of the essential pseudospectra by means of the measure of noncompactness, and we give sufficient conditions on the perturbed operator to have its invariance. Copyright © 2013 John Wiley & Sons, Ltd. |
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| Keywords: | measures of noncompactness in Banach spaces essential pseudospectra compact operators Fredholm operators |
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