scholarly journals Perturbation results in the Fredholm theory and m-essential spectra of some matrix operators

Filomat ◽  
2021 ◽  
Vol 35 (7) ◽  
pp. 2141-2149
Author(s):  
Boulbeba Abdelmoumen ◽  
Sadok Chakroun ◽  
Mnif Maher
Keyword(s):  
Banach Spaces ◽  
Essential Spectrum ◽  
Fredholm Theory ◽  
Essential Spectra ◽  
Matrix Operators

In this paper, we will use some new properties of non-compactness measure, in order to establish a description of the M-essential spectrum for some matrix operators on Banach spaces.

The Essential Spectrum of Some Matrix Operators

1994 ◽  
Vol 167 (1) ◽  
pp. 5-20 ◽  
Author(s):  
F. V. Atkinson ◽  
H. Langer ◽  
R. Mennicken ◽  
A. A. Shkalikov
Keyword(s):  
Essential Spectrum ◽  
Matrix Operators

scholarly journals Some New Properties in Fredholm Theory, Schechter Essential Spectrum, and Application to Transport Theory

2008 ◽  
Vol 2008 ◽  
pp. 1-14 ◽  
Author(s):  
Boulbeba Abdelmoumen ◽  
Abdelkader Dehici ◽  
Aref Jeribi ◽  
Maher Mnif
Keyword(s):  
Essential Spectrum ◽  
Transport Theory ◽  
Fredholm Theory

Essential Spectra of General Second-Order Differential Operators

2018 ◽  
Author(s):  
D. E. Edmunds ◽  
W. D. Evans
Keyword(s):  
Essential Spectrum ◽  
Distance Function ◽  
Differential Operators ◽  
Second Order ◽  
Compact Perturbation ◽  
Essential Spectra ◽  
Sectorial Operators

In this chapter, the operators considered are those m-sectorial operators discussed in Chapter VII, and the essential spectra are the sets defined in Chapter IX that remain invariant under compact perturbation. A generalization of a result of Persson is used to determine the least point of the essential spectrum. Davies’ mean distance function is introduced and consequences investigated.

scholarly journals On joint essential spectra of doubly commuting n-tuples of p-hyponormal operators

1998 ◽  
Vol 40 (3) ◽  
pp. 353-358 ◽  
Author(s):  
In Ho Jeon
Keyword(s):  
Essential Spectrum ◽  
Polar Decomposition ◽  
Essential Spectra ◽  
Weyl Spectrum ◽  
Hyponormal Operators ◽  
Image Position

AbstractLet A be an operator on a Hillbert space with polar decomposition A = |A|, let  = |A|½U|A|½ and let  = V|Â| be the polar decomposition of Â. Write à for the operatorà = |Â|½V|Â|½. If = (A1,…,AN) is a doubly commuting n-tuple of p-hyponormal operators on a Hillbert space with equal defect and nullity, then = (Ã1,…,Ãn) is a doubly commuting n-tuple of hyponormal operators. In this paper we show thatwhere σ* denotes σTe (Taylor essential spectrum), σTw (Taylor-Weyl spectrum) and σTb (Taylor-Browder spectrum), respectively.

scholarly journals Norm estimates for matrix operators between Banach spaces

2013 ◽  
Vol 438 (3) ◽  
pp. 986-1001 ◽  
Author(s):  
Mieczysław Mastyło ◽  
Paweł Mleczko
Keyword(s):  
Banach Spaces ◽  
Norm Estimates ◽  
Matrix Operators

Stability of some essential spectra of closed linear relations on Banach spaces

2018 ◽  
Vol 29 (7-8) ◽  
pp. 987-993 ◽  
Author(s):  
Aymen Ammar ◽  
Omar Jedidi ◽  
Aref Jeribi
Keyword(s):  
Banach Spaces ◽  
Essential Spectra ◽  
Linear Relations
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