Coupled coincidence points for two mappings in metric spaces and cone metric spaces

This article is concerned with coupled coincidence points and common fixed points for two mappings in metric spaces and cone metric spaces. We first establish a coupled coincidence point theorem for two mappings and a common fixed point theorem for two $w$-compatible mappings in metric spaces. Then, by using a scalarization method, we extend our main theorems to cone metric spaces. Our results generalize and complement several earlier results in the literature. Especially, our main results complement a very recent result due to Abbas et al

Some notes on the paper “The equivalence of cone metric spaces and metric spaces”

In this article, we shall show that the metrics defined by Feng and Mao, and Du are equivalent. We also provide some examples for one of the metrics

Double absolute summability factor theorems and applications

In an earlier paper the first author [Ekrem Savas, Factors for | A |k summability of infinite series, Comput. Math. Appl. 53 (7) (2007) 1045-1049. [3]] obtained a summability factor theorem for absolute summability of the order k ? 1. In this paper we extend that result to doubly infinite matrices. © 2007 Elsevier Ltd. All rights reserved

Every conservative double Hausdorff matrix is a kth absolutely summable operator

Let A denote the set of kth absolutely summable double series. In this paper it is shown that every double conservative Hausdorff matrix is a bounded operator on A. © 2009 Akadémiai Kiadó, Budapest

Convergence of an Ishikawa-Type Iteration Scheme for a Generalized Contraction

AbstractWe show that the result of Xu [J. Math. Anal. Appl.167 (1992), 582-587], dealing with an Ishikawa-type iteration for a map T satisfying Ćirić′s definition [Proc. Amer. Math. Soc.], can be extended to a wider class of maps

Inclusion Theorems for Absolute Matrix Summability Methods

AbstractIn this paper we establish a general inclusion theorem for a nonnegative lower triangular matrix to be absolutely stronger than a weighted mean matrix. Several inclusion theorems for Cesàro and weighted mean methods are then obtained as corollaries