概率度量空间中的Ekeland变分原理与集值映象的Caristi重合定理

借助偏序方法,本文得到概率度量空间中之一推广形式的Ekeland变分原理及一集值形式的Caristi重合定理,同时证明了这两个定理之间的等价性.本文结果是[1,2,5,6,7,9]中相应结果的改进和推广.     

集值的Caristi不动点定理与Ekeland变分原理

本文提出一条加强形式的集值映象的Caristi不动点定理,并用较简单的方法证明了Ekeland变分原理与这一加强形式的集值的Caristi不动点定理的等价性.本文的结果改进和加强了[4]中的相应结果.     

Caristi不动点定理的推广

设X是距离空间，又是半序集，A：X→X是一个算子，满足对任给x∈X，都有x≤Ax。本文给出了A存在不动点的若干充分性条件，推广了著名的Caristi不动点定理。     

有界线性空间中含有Q-距离的Ekeland变分原理

有界线性空间中引入了Q-距离的概念,建立了一类向量值Ekeland变分原理,其目标函数是从有界线性空间映到锥序的实线性空间,并且扰动项中含有Q-距离．由此可以得到有界线性空间中现有的一些Ekeland变分原理．同时建立了有界线性空间中的向量值Caristi不动点定理,也给出二者的等价性．     

Fuzzy度量空间中的单值映射的Caristi型不动点定理

本文采用Ｋａｌａｖａ和Ｓｅｉｋｋａｌａ的模糊度量空间定义，利用文（７）中建立的亚度量簇生成空间理论，研究了Ｆｕｚｚｙ度量空间中的单值映射的Ｃａｒｉｓｔｉ型不动点定理以及它在Ｍｅｎｇｅｒ概率度量空间中的应用。     

一类Ekeland变分原理的推广

本文给出一个向量值形式的Ekeland变分原理,其目标函数是从完备的度量空间映到锥序拓扑线性空间.此结果是对钟承奎建立的Ekeland变分原理的推广.     

可数半范空间中Ekeland变分原理的一种形式

本文给出了可数半范空间中Ekeland变分原理的一种新的形式.     

Menger概率度量空间中Caristi型混合不动点定理

本文在Menger概率度量空间中引进Caristi型混合不动点概念,得到两个混合不动点定理和两个集值映象序列的公共混合不动点定理,我们的定理改进和推广了Caristi不动点定理及相关的近期重要结果.     

Fuzzy度量空间中Fuzzy映象的重合定理与Ekeland‘s变分原理

本文给出了Ｆｕｚｚｙ度量空间中Ｆｕｚｚｙ映射的重合定理，推广了文（３）（５）中主要的结果。     

局部凸空间中的Drop定理,Phelps引理和Ekeland变分原理的推广

在局部凸空间框架下,我们利用Drop定理,Phelps引理和Ekeland变分原理的赋范线性空间的形式对其分别进行了推广.并且阐述了这些定理之间以及和它们赋范线性空间的形式之间是等价的.     

The Schauder fixed point theorem in geodesic spaces

We give a direct proof of Schauder's fixed point theorem in the setting of geodesic metric spaces, generalizing the classical Schauder's theorem and improving a recent version of this theorem in CAT(κ)$\mathrm{CAT}(\kappa )$ spaces. As an application we prove an existence result for a variational inequality in the setting of CAT(κ)$\mathrm{CAT}(\kappa )$ spaces.     

Compression-expansion fixed point theorem in two norms and applications

In this paper we present a two-norms version of Krasnoselskii's fixed point theorem in cones. The abstract result is then applied to prove the existence of positive Lp solutions of Hammerstein integral equations with better integrability properties on the kernels.     

Strong convergence theorem of an iterative method for variational inequalities and fixed point problems in Hilbert spaces

In this paper, we introduce a new iteration method based on the hybrid method in mathematical programming and the descent-like method for finding a common element of the set of solutions for a variational inequality and the set of fixed points for a nonexpansive mapping in Hilbert spaces. Our method modifies and improves some methods in literature.     

On variational inclusion and common fixed point problems in Hilbert spaces with applications

The purpose of this paper is to introduce a general iterative method for finding a common element of the solution set of quasi-variational inclusion problems and of the common fixed point set of an infinite family of nonexpansive mappings in the framework Hilbert spaces. Strong convergence of the sequences generated by the purposed iterative scheme is obtained.     

Ekeland's variational principle and Caristi's fixed point theorem in probabilistic metric space

The main purpose of this paper is to establish the Ekeland's variational principle and Caristi's fixed point theorem in probabilistic metric spaces and to give a direct simple proof of the equivalence between these two theorems in the probabilistic metric space. The results presented in this paper generalize the corresponding results of [9–12].The project is supported by National Natural Science Foundation of China.     

Comment on: A new fixed point theorem in the fractal space

In this paper, we give a counterexample to Lemma 2.2 proved by Song-il Ri (2016). Further, we improve the result of Song-il Ri by employing a proper setting.     

Some generalizations of Ekeland-type variational principle with applications to equilibrium problems and fixed point theory

In this paper, we introduce the concept of a Q$Q$-function defined on a quasi-metric space which generalizes the notion of a τ$\tau$-function and a w$w$-distance. We establish Ekeland-type variational principles in the setting of quasi-metric spaces with a Q$Q$-function. We also present an equilibrium version of the Ekeland-type variational principle in the setting of quasi-metric spaces with a Q$Q$-function. We prove some equivalences of our variational principles with Caristi–Kirk type fixed point theorems for multivalued maps, the Takahashi minimization theorem and some other related results. As applications of our results, we derive existence results for solutions of equilibrium problems and fixed point theorems for multivalued maps. We also extend the Nadler’s fixed point theorem for multivalued maps to a Q$Q$-function and in the setting of complete quasi-metric spaces. As a consequence, we prove the Banach contraction theorem for a Q$Q$-function and in the setting of complete quasi-metric spaces. The results of this paper extend and generalize many results appearing recently in the literature.     

Algorithms of common solutions for variational inclusions, mixed equilibrium problems and fixed point problems

In this paper, we present an iterative algorithm for finding a common element of the set of solutions of a mixed equilibrium problem and the set of fixed points of an infinite family of nonexpansive mappings and the set of a variational inclusion in a real Hilbert space. Furthermore, we prove that the proposed iterative algorithm has strong convergence under some mild conditions imposed on algorithm parameters.     

On a fixed point theorem of Kirk

W.A. Kirk [J. Math. Anal. Appl. 277 (2003) 645-650] first introduced the notion of asymptotic contractions and proved the fixed point theorem for this class of mappings. In this note we present a new short and simple proof of Kirk's theorem.