Home Operators that are Weakly Coercive and a Compact Perturbation
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Operators that are Weakly Coercive and a Compact Perturbation

  • José María Soriano Arbizu EMAIL logo and Manuel Ordoñez Cabrera
Published/Copyright: December 18, 2023
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ABSTRACT

Let X, Y be two Banach spaces over K= or , and let f := F+C be a weakly coercive operator from X onto Y, where F is a Fredholm proper operator, and C is a C1-compact operator. Sufficient conditions are provided to assert that the perturbed operator f is a C1-diffeomorphism. When one of these conditions does not hold and instead y is a regular value, the equation f(x) = y has at most finite number of solutions. As a consequence of the main result two corollaries are given. A second theorem studies the finite dimensional case. As an application, one example is given. The proof of our results is based on properties of Fredholm operators, as well as on local and global inverse mapping theorems.

2020 Mathematics Subject Classification: Primary 47H14; Secondary 47A55

(Communicated by Tomasz Natkaniec)


Funding statement: The authors have been partially supported by the Plan Andaluz de Investigación de la Junta de Andalucía FQM-127 Grant P08-FQM-03543, and by MEC Grant MTM2015-65242-C2-1-P.

Acknowledgement

The authors are very grateful to the referee for carefully reading the manuscript and for offering substantial comments and suggestions which enabled them to improve the paper.

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Received: 2022-04-28
Accepted: 2023-01-13
Published Online: 2023-12-18

© 2023 Mathematical Institute Slovak Academy of Sciences

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