Abstract Let X X and Y Y be non-Archimedean Banach spaces over K {\mathbb{K}} , A ∈ B ( X , Y ) A\in B\left(X,Y) and B ∈ B ( Y , X ) B\in B\left(Y,X) such that A B A = A 2 ABA={A}^{2} and B A B = B 2 . BAB={B}^{2}. In this article, we investigate some properties of the operator equations A B A = A 2 ABA={A}^{2} and B A B = B 2 BAB={B}^{2} , and many common basic properties of I Y − A B {I}_{Y}-AB and I X − B A {I}_{X}-BA are given. In particular, if X X and Y Y are Banach spaces over a spherically complete field K , {\mathbb{K}}, then N ( I Y − A B ) N\left({I}_{Y}-AB) is a complemented subspace of Y Y if and only if N ( I X − B A ) N\left({I}_{X}-BA) is a complemented subspace of X . X. Finally, we give some examples to illustrate our work.
We introduce the concept of generalized suprametric spaces, which subsumes some existing abstract metric spaces. Then, we show the existence of fixed points for maps satisfying nonlinear contractions involving either extended comparison or ρ\rho -subhomogeneous functions. This study was carried out in generalized suprametric spaces as well as partially ordered generalized suprametric spaces. Some related results in JS-metric spaces and in bb-suprametric spaces are improved or extended.
Recently, Abbas et al. [Enriched multivalued contractions with applications to differential inclusions and dynamic programming, Symmetry 13(8) (2021), 1350] obtained an interesting generalization of the Nadler fixed point theorem by introducing the concept of enriched multivalued contraction in the framework of Banach spaces. In this article, we define a new class of metrics on the family of closed and bounded subsets of a given metric space. Furthermore, fixed point theorems were established for enriched multi-valued contractions by substituting the Hausdorff metric with metrics from a specific class that are either metrically or sequentially equivalent to the Hausdorff metric. Some examples are provided to illustrate the concepts and results presented herein. These results improve, unify, and generalize several comparable results in the literature.
Using the class of (μ,σ)\left(\mu ,\sigma )-nonexpansive mappings, we will effectively prove the uniqueness of the approximative fixed points set for equivalent nn-linear functional spaces F{\mathscr{F}}, where F{\mathscr{F}} is nonempty and identical in every bounded case in nn-Banach space.
This work establishes a connection between the class of generalized lower characteristic operators and [⋅]a{\left[\cdot ]}_{a} acting on a Banach space involving measures of non-strict singularity. This study presents findings on the Jeribi essential spectra of the sum of two bounded linear operators and the Jeribi essential spectra of each operator. The results are based on certain requirements related to the measure of non-strict singularity of Fredholm inverses on a Banach space X. A particular application is provided.
