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.     

σ半凸性与Ekeland变分原理

本文引进了σ半凸性,并给出了局部凸空间中一般的Ekeland变分原理.     

广义Ekeland变分原理的应用

研究了广义Ekeland变分原理在拟度量空间中的一些重要应用.利用广义Ekeland变分原理证明了函数f满足关于α的Takahashi ε-条件当且仅当f满足关于相同α的Hamel ε-条件.此外,利用关于α的Takahashi ε-条件得到了一些重要结论.     

Ekeland变分原理的推广及Caristi不动点定理在半度量空间的推广形式

本证明了半度量空间中的Ekeland变分原理及Caristic不动点定理．进而证明了半度量空间中的压缩映像原理。     

局部完备局部凸空间中的向量值变分原理

给出了局部完备局部凸空间中的向量值Ekeland变分原理,并以次可加、严格增的连续函数作为扰动.     

关于局部凸空间中向量Ekeland变分原理的等价性

基于各种Ekeland变分原理的等价形式, 主要研究局部凸空间中给定有界凸子集乘以距离函数为扰动的单调半连续映射的向量Ekeand变分原理的等价性问题. 首先利用局部凸空间中的向量Ekeland变分原理证明了向量Caristi-Kirk不动点定理,向量 Takahashi非凸极小化定理和向量Oettli-Th\'{e}ra定理. 进一步研究了向量Ekeland变分原理与向量Caristi-Kirk不动点定理,向量Takahashi非凸极小化定理和向量Oettli-Th\'{e}ra定理的等价性.     

基于改进集的集值Ekeland变分原理

Ekeland变分原理在最优化理论及应用研究中具有十分重要的作用.利用非线性标量化函数及相应的非凸分离定理建立了基于改进集的集值Ekeland变分原理.新的Ekeland变分原理包含了一些经典的Ekeland变分原理作为其特例.     

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．     

Ekeland变分原理的一种推广

研究完备度量空间中一类拟均衡问题的可解性,由此导出名的Ekeland变分原理。     

拓扑线性空间中的Drop定理

本文在拓扑线性空间中建立了一般的Drop定理并证明新的Drop定理与拓扑线性空间中的一个Ekeland变分原理型的结果等价.此外,还给出了一个无界Drop情形下的Drop定理.     

Local completeness, drop theorem and Ekeland's variational principle

By using a very general drop theorem in locally convex spaces we obtain some extended versions of Ekeland's variational principle, which only need assume local completeness of some related sets and improve Hamel's recent results. From this, we derive some new versions of Caristi's fixed points theorems. In the framework of locally convex spaces, we prove that Daneš' drop theorem, Ekeland's variational principle, Caristi's fixed points theorem and Phelps lemma are equivalent to each other.     

Ekeland's variational principle in locally convex spaces and the density of extremal points

In this paper, we prove a general version of Ekeland's variational principle in locally convex spaces, where perturbations contain subadditive functions of topology generating seminorms and nonincreasing functions of the objective function. From this, we obtain a number of special versions of Ekeland's principle, which include all the known extensions of the principle in locally convex spaces. Moreover, we give a general criterion for judging the density of extremal points in the general Ekeland's principle, which extends and improves the related known results.     

Vectorial variational principle with variable set-valued perturbation

We give a general vectorial Ekeland's variational principle, where the objective function is defined on an F-type topological space and taking values in a pre-ordered real linear space. Being quite different from the previous versions of vectorial Ekeland's variational principle, the perturbation in our version is no longer only dependent on a fixed positive vector or a fixed family of positive vectors. It contains a family of set-valued functions taking values in the positive cone and a family of subadditive functions of topology generating quasi-metrics. Hence, the direction of the perturbation in the new version is a family of variable subsets which are dependent on the ob jective function values. The general version includes and improves a number of known versions of vectorial Ekeland's variational principle. From the general Ekeland's principle, we deduce the corresponding versions of Caristi–Kirk's fixed point theorem and Takahashi's nonconvex minimization theorem. Finally, we prove that all the three theorems are equivalent to each other.     

The density of extremal points in Ekeland's variational principle

In this paper, we investigate the density of extremal points appeared in Ekeland's variational principle. By introducing radial intersections of sets, we give a very general result on the density of extremal points in the framework of locally convex spaces. This solves a problem proposed by G. Isac in 1997. From the general result we deduce several convenient criterions for judging the density of extremal points, which extend and improve a result of F. Cammaroto and A. Chinni. Using the equivalence between Ekeland's variational principle and Caristi's fixed point theorem, we obtain some density results on Caristi's fixed points.     

Ekeland's variational principle, minimax theorems and existence of nonconvex equilibria in complete metric spaces

In this paper, we introduce the concept of τ-function which generalizes the concept of w-distance studied in the literature. We establish a generalized Ekeland's variational principle in the setting of lower semicontinuous from above and τ-functions. As applications of our Ekeland's variational principle, we derive generalized Caristi's (common) fixed point theorems, a generalized Takahashi's nonconvex minimization theorem, a nonconvex minimax theorem, a nonconvex equilibrium theorem and a generalized flower petal theorem for lower semicontinuous from above functions or lower semicontinuous functions in the complete metric spaces. We also prove that these theorems also imply our Ekeland's variational principle.     

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.     

A unified theory of necessary conditions for nonlinear nonconvex control systems

We consider optimal problems for a general nonlinear nonconvex input-output relation for Banach space valued functions. A maximum principle is obtained using Ekeland's variational principle. The formulation applies to systems described by ordinary differential equations, functional differential equations, and partial differential equations (both for distributed and boundary control systems).This work was supported in part by the National Science Foundation under Grant No. DMS-8200645.