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Coupled fixed points of mixed monotone operators on probabilistic Banach spaces

Ismat Beg, Abdul Latif, Rashid Ali, Akbar Azam (2001)

Archivum Mathematicum

The existence of minimal and maximal fixed points for monotone operators defined on probabilistic Banach spaces is proved. We obtained sufficient conditions for the existence of coupled fixed point for mixed monotone condensing multivalued operators.

Functional calculus for a class of unbounded linear operators on some non-archimedean Banach spaces

Dodzi Attimu, Toka Diagana (2009)

Commentationes Mathematicae Universitatis Carolinae

This paper is mainly concerned with extensions of the so-called Vishik functional calculus for analytic bounded linear operators to a class of unbounded linear operators on c 0 . For that, our first task consists of introducing a new class of linear operators denoted W ( c 0 ( J , ω , 𝕂 ) ) and next we make extensive use of such a new class along with the concept of convergence in the sense of resolvents to construct a functional calculus for a large class of unbounded linear operators.

Invariant approximation for fuzzy nonexpansive mappings

Ismat Beg, Mujahid Abbas (2011)

Mathematica Bohemica

We establish results on invariant approximation for fuzzy nonexpansive mappings defined on fuzzy metric spaces. As an application a result on the best approximation as a fixed point in a fuzzy normed space is obtained. We also define the strictly convex fuzzy normed space and obtain a necessary condition for the set of all t -best approximations to contain a fixed point of arbitrary mappings. A result regarding the existence of an invariant point for a pair of commuting mappings on a fuzzy metric...

On quasi-compactness of operator nets on Banach spaces

Eduard Yu. Emel'yanov (2011)

Studia Mathematica

The paper introduces a notion of quasi-compact operator net on a Banach space. It is proved that quasi-compactness of a uniform Lotz-Räbiger net ( T λ ) λ is equivalent to quasi-compactness of some operator T λ . We prove that strong convergence of a quasi-compact uniform Lotz-Räbiger net implies uniform convergence to a finite-rank projection. Precompactness of operator nets is also investigated.

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