<abstract xmlns="http://www.w3.org/1999/xhtml">Let (<italic>C</italic>(<italic>t))t</italic>∈𝕉 be a strongly continuous cosine family and <italic>A</italic> be its infinitesimal generator. In this work, we prove that, if <italic>C</italic>(<italic>t</italic>) – coshλ<italic>t</italic> is Saphar (resp. quasi-Fredholm) operator and λ<italic>t</italic> /∉<italic>iπ</italic>𝕑, then <italic>A –</italic> λ2 is also Saphar (resp. quasi-Fredholm) operator. We show by counter-example that the converse is false in general.</abstract>

Let (C(t))t∈𝕉 be a strongly continuous cosine family and A be its infinitesimal generator. In this work, we prove that, if C(t) – coshλt is Saphar (resp. quasi-Fredholm) operator and λt /∉iπ𝕑, then A – λ2 is also Saphar (resp. quasi-Fredholm) operator. We show by counter-example that the converse is false in general.

On the quasi-Fredholm and Saphar spectrum of strongly continuous Cosine operator function

Department of Mathematics and Computer Science, Pluridisciplinary Faculty of Nador

Moroccan Journal of Pure and Applied Analysis

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Let (C(t))t∈𝕉 be a strongly continuous cosine family and A be its infinitesimal generator. In this work, we prove that, if C(t) – coshλt is Saphar (resp....

On the quasi-Fredholm and Saphar spectrum of strongly continuous Cosine operator function

Data publikacji: 22 lis 2020

Zakres stron: 80 - 87

Otrzymano: 08 sie 2020

Przyjęty: 08 lis 2020

DOI: https://doi.org/10.2478/mjpaa-2021-0008

Słowa kluczowe
Cosine, Quasi-Fredholm, Semi-regular, Saphar

© 2020 Hamid Boua, published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

On the quasi-Fredholm and Saphar spectrum of strongly continuous Cosine operator function

Data publikacji: 22 lis 2020

Zakres stron: 80 - 87

Otrzymano: 08 sie 2020

Przyjęty: 08 lis 2020

DOI: https://doi.org/10.2478/mjpaa-2021-0008

Słowa kluczoweCosine, Quasi-Fredholm, Semi-regular, Saphar

© 2020 Hamid Boua, published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Słowa kluczowe
Cosine, Quasi-Fredholm, Semi-regular, Saphar