In this paper, we generalize the Meir-Keeler condensing  operators  via a concept of the class of operators  $ O (f;.)$, that was given by Altun and Turkoglu [4], and apply this extension to obtain some tripled fixed point theorems.  As an application of this extension, we  analyze the existence of solution for a system of nonlinear functional integral equations of Volterra type. Finally,  we p...

In this paper, we consider a nonlinear third-order three-point boundary value problem and give the existence uniqueness of solutions by constructing Green’s function using its properties. The methods used here are based on Darbo’s fixed point theorem combined with technique measure noncompactness. Finally, as applications, two examples given to illustrate our main results.

We give some results concerning stability in the Fredholm operators and Browder operators set, via the concept of measure of noncompactness. Moreover, we prove some localization results on the essential spectra of bounded operators on Banach space. As application, we describe the essential spectra of weighted shift operators. Finally, we describe the spectra of polynomially compact operators, a...