Extensions of Edelstein's Theorem on Contractive Mappings

The aim of this article is to provide extensions of Edelstein's theorem for a class of contractive mappings, namely cyclic contractive mappings. We prove the existence and convergence of best proximity points of a cyclic contractive map. We also discuss continuity properties of cyclic contractive maps. Finally, we give a characterization of such maps in the setting of a Hilbert space.     

Best Proximity Points and Fixed Points Results for Noncyclic and Cyclic Fisher Quasi-contractions

In this article, in the setting of metric spaces we introduce the notions of noncyclic and cyclic Fisher quasi-contraction mappings. We establish the existence of an optimal pair of fixed points for a noncyclic Fisher quasi-contraction mapping and iterative algorithms are furnished to determine such optimal pair of fixed points. For a cyclic Fisher quasi-contraction mapping, we also study the existence of best proximity points. Presented results extend and improve some recent results in the literature.     

On Bregman Best Proximity Points in Banach Spaces

In this article, using Bregman functions and Bregman distances, we first introduce the notion of Bregman best proximity points, extending the notion of best proximity points introduced and studied in [1 K. Fan (1969). Extensions of two mixed point theorems of F. E. Browder. Math. Z. 122:234–240.[Crossref], [Web of Science ®] , [Google Scholar]]. We then prove existence and convergence results of Bregman best proximity points for Bregman cyclic contraction mappings in the setting of Banach spaces. It is well known that the Bregman distance does not satisfy either the symmetry property or the triangle inequality which are required for standard distances. Numerical examples are included at the end of the paper. So, our results improve and generalize many known results in the current literature.     

Best Proximity Point Theorems for Some Special Proximal Contractions

This article explores some new best proximity point theorems for absolute proximal cyclic contractions and dual supreme proximal contractions which are not necessarily continuous. As a consequence of such best proximity point theorems, the famous contraction principle is elicited.     

关于最近点对及近渡点存在性与唯一性

给定两个不主集合Ｆ，Ｇ研究最近点对（ｘ，ｙ）存在性及与近距映射Ｐ_Ｇｘ_０，Ｐ_rｙ０的关系，以及与近渡点存在的关系。又引入严凸集，它对研究最近点对唯一性与近渡点唯一性起重要作用，而Ｆ，Ｇ一个严凸，一个凸的仍不保证唯一性，除非在严凸空间情形．     

Best Proximity Pair Results for Relatively Nonexpansive Mappings in Geodesic Spaces

Given A and B two nonempty subsets in a metric space, a mapping T: A ∪ B → A ∪ B is relatively nonexpansive if d(Tx, Ty) ≤ d(x, y) for every x ∈ A, y ∈ B. A best proximity point for such a mapping is a point x ∈ A ∪ B such that d(x, Tx) = dist(A, B). In this work, we extend the results given in Eldred et al. (2005) [A.A. Eldred, W.A. Kirk, P. Veeramani, Proximal normal structure and relatively nonexpansive mappings, Studia Math. 171, 283–293] for relatively nonexpansive mappings in Banach spaces to more general metric spaces. Namely, we give existence results of best proximity points for cyclic and noncyclic relatively nonexpansive mappings in the context of Busemann convex reflexive metric spaces. Moreover, particular results are proved in the setting of CAT(0) and uniformly convex geodesic spaces. Finally, we show that proximal normal structure is a sufficient but not necessary condition for the existence in A × B of a pair of best proximity points.     

Best Proximity Points and Fixed Point Results for Certain Maps in Banach Spaces

In this article, we establish some new existence theorems for best proximity point and fixed point problems for certain mappings in Banach spaces. The main results of this article improve and extend the results presented by Wong [25 C. Wong ( 1974 ). Fixed points and characterizations of certain maps . Pacific J. Math. 54 : 305 – 312 .[Crossref], [Web of Science ®] , [Google Scholar]]. Examples are given to support the usability of our main conclusions.     

Existence and Convergence Theorems for Global Minimization of Best Proximity Points in Hilbert Spaces

In order to solve global minimization problems involving best proximity points, we introduce general Mann algorithm for nonself nonexpansive mappings and then prove weak and strong convergence of the proposed algorithm under some suitable conditions in real Hilbert spaces. Furthermore, we also provide numerical experiment to illustrate the convergence behavior of our proposed algorithm.

     

Convergence of Picard’s iteration using projection algorithm for noncyclic contractions

Given $A$ and$B$ two nonempty subsets of a metric space, a mapping $T:A\cup B\to A\cup B$ is noncyclic provided that $T\left(A\right)?A$ and $T\left(B\right)?B$. A point $(p,q)\in A\times B$ is called a best proximity pair for the noncyclic mapping $T$ if $p=Tp,q=Tq$ and $d(p,q)=\mathrm{dist}(A,B)$. In this article, we survey the convergence of Picard’s iteration to a best proximity pair for noncyclic contractions using a projection algorithm in uniformly convex Banach spaces, where the initial point is in the proximal set of $A$. We also provide some sufficient conditions to ensure the existence of a common best proximity pairs for a pair of noncyclic mappings.     

A note on “Convergence and best proximity points for Berinde's cyclic contraction with proximally complete property”

Recently, Sanhan and Mongkolkeha introduced the concept of Berinde's cyclic contraction, and they established some results. Unfortunately, these results seem to be incorrect. In this paper, some counterexamples are given.     

Note on Norm and Pointwise Convergence of Exponential Products and their Integral Kernels for the Harmonic Oscillator

The aim of this paper is to study the exponential symmetric product formula for the semigroup of the one-dimensional harmonic oscillator to discuss its convergence pointwise of the integral kernels as well as in norm with sharp optimal error bound.      

一类随机减算子随机不动点存在唯一性定理及应用

该文在没有任何连续性和紧性条件下, 得到了一类随机减算子随机不动点存在唯一性定理, 并由此给出了应用到随机积分方程的两个例子.     

Banach关于增生算子零点的修正Mann迭代的注

A more general form of modified Mann iterations which converges strongly to a zero point of an m-accretive operator is given. The work in this paper is an extension and complement of the corresponding result of Kim T.H. and Xu H.K in 2005     

A Note on the Rate of Complete Convergence for Weighted Sums of Arrays of Banach Space Valued Random Elements

A rate of complete convergence for weighted sums of arrays of rowwise independent Banach space valued random elements was obtained by Ahmed et al. [1 Ahmed , S.E. , Giuliano Antonini , R. , and Volodin , A. 2002 . On the rate of complete convergence for weighted sums of arrays of Banach space valued random elements with application to moving average processes . Statist. Probab. Lett. 58 : 185 – 194 . [Google Scholar]]. Recently, Sung and Volodin [2 Sung , S.H. , and Volodin , A.I. 2006. On the rate of complete convergence for weighted sums of arrays of random elements. J. Korean Math. Soc. 43:815–828.[Crossref], [Web of Science ®] , [Google Scholar]], Chen et al. [3 Chen , P. , Sung , S.H. , and Volodin , A.I. 2006 . Rate of complete convergence for arrays of Banach space valued random elements . Siberian Adv. Math. 16 : 1 – 14 . [Google Scholar]], and Kim and Ko [4 Kim , T.S. , and Ko , M.H. 2008 . On the complete convergence of moving average process with Banach space valued random elements . J. Theor. Probab. 21 : 431 – 436 . [Google Scholar]] solved an open question posed by Ahmed et al. In this article, we improve and complement the result of Ahmed et al. The method used in this article is simpler than those in Ahmed et al., Sung and Volodin, Chen et al., and Kim and Ko.     

Best Constants for Moser-Trudinger Inequalities, Fundamental Solutions and One-Parameter Representation Formulas on Groups of Heisenberg Type

We derive the explicit fundamental solutions for a class of degenerate (or singular) one-parameter subelliptic differential operators on groups of Heisenberg (H) type. This extends the results of Kaplan of the sub-Laplacian on H-type groups, which in turn generalizes Folland's result on the Heisenberg group. As an application, we obtain a one-parameter representation formula for Sobolev functions of compact support on H-type groups. By choosing the parameter equal to the homogeneous dimension Q and using the Moser-Trudinger inequality for the convolutional type operator on stratified groups obtained in [18], we get the following theorem which gives the best constant for the Moser-Trudinger inequality for Sobolev functions in H-type groups. Let ${\Bbb G}We derive the explicit fundamental solutions for a class of degenerate (or singular) one-parameter subelliptic differential operators on groups of Heisenberg (H) type. This extends the results of Kaplan of the sub-Laplacian on H-type groups, which in turn generalizes Folland's result on the Heisenberg group. As an application, we obtain a one-parameter representation formula for Sobolev functions of compact support on H-type groups. By choosing the parameter equal to the homogeneous dimension Q and using the Moser-Trudinger inequality for the convolutional type operator on stratified groups obtained in [18], we get the following theorem which gives the best constant for the Moser-Trudinger inequality for Sobolev functions in H-type groups. Let ? be any group of Heisenberg type whose Lie algebra is g enerated by m left invariant vector fields and with a q-dimensional center. Let and Then, with A _Q as the sharp constant, where ∇_? denotes the subellitpic gradient on ? This continues the research originated in our earlier study of the best constants in Moser-Trudinger inequalities and fundamental solutions for one-parameter subelliptic operators on the Heisenberg group [18]. Received March 15, 2001, Accepted September 21, 2001     

对“关于第一类不连续点函数的介值定理和积分中值定理”一文的注记

利用只有第一类不连续点函数的介值定理和勒贝格积分理论,建立了至多有第一类不连续点函数的积分中值定理的推广形式,推广了徐永利的结论.     

Existence and uniqueness of invariant measures for a class of transition semigroups on Hilbert spaces

We prove a smoothing property and the irreducibility of transition semigroups corresponding to a class of semilinear stochastic equations on a separable Hilbert space H. Existence and uniqueness of invariant measures are discussed as well.     

A Note on the Recursive and Parallel Structure of the Birge and Qi Factorization for Tree Structured Linear Programs

In this note, we derive the complete recursive structure of the Birge and Qi factorization for interior point methods (IPM) for tree structured linear programs as they appear in multistage stochastic programs. This recursive structure allows for an elegant implementation on parallel hardware, since multiple versions of the same program may be run on on different processors. Our preliminary computational experiment, conducted on a Beowulf cluster, demonstrates the scalability of this approach.     

A short note on the paper “Convergence of the TAGE iterative method for the system arisen from the cubic spline approximation for the solution of two-point BVPs with forcing function in integral form”, by Mohanty, Jain and Dhall

In this note, we point out an error in the recently published article [R.K. Mohanty, M.K. Jain, D. Dhall, A cubic spline approximation and application of TAGE iterative method for the solution of two-point boundary value problems with forcing function in integral form, Appl. Math. Model. 35 (2011) 3036-3047] and then correct it.