Upper triangular operator matrices and limit points of the essential spectrum

Authors

DOI:

https://doi.org/10.22199/issn.0717-6279-2019-03-0026

Keywords:

Fredholm operator, Essential spectra, Limit point, Operator matrices

Abstract

In this paper, we investigate the limit points set of essential spectrum of upper triangular operator matrices We prove that acc?e(MC) ? W = acc?e(A) ? acc?e(B) where W is the union of certain holes in acc?e(MC), which happen to be subsets of acc?e(B) ? acc?e(A). Also, several sufficient conditions for acc?e(MC) = acc?e(A) ? acc?e(B) holds are given.

Author Biographies

Mohammed Karmouni, Cadi Ayyad University.

Department of Mathematics and Computer Science, Faculty Polydisciplinary of Safi.

A. Tajmouati, Sidi Mohamed Ben Abdellah University.

Faculty of Sciences Dhar Al Mahraz, Laboratory of Mathematical Analysis and Applications.

A. A. El Bakkali, Chouaib Doukkali University.

Faculty of Science, Department of Mathematics.

References

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Published

2019-08-06

How to Cite

[1]
M. Karmouni, A. Tajmouati, and A. A. El Bakkali, “Upper triangular operator matrices and limit points of the essential spectrum”, Proyecciones (Antofagasta, On line), vol. 38, no. 3, pp. 401-409, Aug. 2019.

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Section

Artículos