This book exclusively deals with the study of almost convergence and statistical convergence of double sequences. The notion of almost convergence is perhaps the most useful notion in order to obtain a weak limit of a bounded non-convergent sequence. There is another notion of convergence known as the statistical convergence, introduced by H. Fast, which is an extension of the usual concept of sequential limits. This concept arises as an example of convergence in density which is also studied as a summability method. Even unbounded sequences can be dealt with by using this method. The book...

This book's dedicated focus on the 'almost' convergence and statistical convergence of double sequences demystifies the concept using a host of revealing examples, highlighting the application of double sequences in key areas of pure and applied mathematics.

This book publishes original research chapters on the theory of approximation by positive linear operators as well as theory of sequence spaces and illustrates their applications. Chapters are original and contributed by active researchers in the field of approximation theory and sequence spaces. Each chapter describes the problem of current importance and summarizes ways of their solution and possible applications which improve the current understanding pertaining to sequence spaces and approximation theory. The presentation of the articles is clear and self-contained throughout the book.