The aim of this special issue is to focus on recent developments and achievements in the theory of function spaces, sequences spaces and their geometry, and compact operators and their applications in various fields of applied mathematics, engineering, and other sciences. The theory of sequence spaces is powerful tool for obtaining positive results concerning Schauder basis and plays a fundamental role in creating the basis of several investigations conducted in nonlinear analysis. The compactness is very often used in fixed point theory and its applications to the theories of differential, functional differential, integral, and integrodifferential equations.

The research papers in this special issue cover various topics like geometry of Banach spaces, Schauder basis and dual spaces, sequence spaces and their topological and geometric properties, approximation of positive linear operators by matrix and nonmatrix methods, convergence and stability results for iterative process, applications of iterative methods to a nonlinear integral equation, Littlewood-Paley operators on Morrey spaces, matrix transformations between certain sequence spaces, measures of noncompactness and their applications in characterizing compact matrix operators, fixed point theorems and their applications, and so on.


The editors thank all the contributors and colleagues who did the refereeing work very sincerely.

S. A. Mohiuddine
M. Mursaleen
Józef Banaś
Suthep Suantai
Abdullah Alotaibi