PPA BASED PREDICTION-CORRECTION METHODS FOR MONOTONE VARIATIONAL INEQUALITIES

In this paper we study the proximal point algorithm (PPA) based prediction-correction (PC) methods for monotone variational inequalities. Each iteration of these methods consists of a prediction and a correction. The predictors are produced by inexact PPA steps. The new iterates are then updated by a correction using the PPA formula. We present two profit functions which serve two purposes: First we show that the profit functions are tight lower bounds of the improvements obtained in each iteration. Based on this conclusion we obtain the convergence inexactness restrictions for the prediction step. Second we show that the profit functions are quadratically dependent upon the step lengths, thus the optimal step lengths are obtained in the correction step. In the last part of the paper we compare the strengths of different methods based on their inexactness restrictions.     

A MODIFIED VARIABLE-PENALTY ALTERNATING DIRECTIONS METHOD FOR MONOTONE VARIATIONAL INEQUALITIES

Alternating directions method is one of the approaches for solving linearly constrained separate monotone variational inequalities. Experience on applications has shown that the number of iteration significantly depends on the penalty for the system of linearly constrained equations and therefore the method with variable penalties is advantageous in practice. In this paper, we extend the Kontogiorgis and Meyer method [12] by removing the monotonicity assumption on the variable penalty matrices. Moreover, we introduce a self-adaptive rule that leads the method to be more efficient and insensitive for various initial penalties. Numerical results for a class of Fermat-Weber problems show that the modified method and its self-adaptive technique are proper and necessary in practice.     

一类求解单调变分不等式的隐式方法

1．引言变分不等式是一个非常有趣。非常困难的数学问题［"］．它具有广泛的应用（例如，数学规划中的许多基本问题都可以归结为一个变分不等式问题），因而得到深入的研究并有了不少算法［1，2，5－8，17－21］．对线性单调变分不等式，我们最近提出了一系列投影收缩算法Ig－13］．本文考虑求解单调变分不等式其中0CW是一闭凸集，F是从正p到自身的一个单调算子，一即有我们用比（·）表示到0上的投影．求解单调变分不等式的一个简单方法是基本投影法［1，6］，它的迭代式为然而，如果F不是仿射函数，只有当F一致强单调且LIPSChitZ连续…     

ALTERNATING PROJECTION BASED PREDICTION-CORRECTION METHODS FOR STRUCTURED VARIATIONAL INEQUALITIES

The monotone variational inequalities Ⅵ(Ω,F)have vast applications, including opti-mal controls and convex programming.In this paper we focus on the Ⅵ problems thathave a particular splitting structure and in which the mapping F does not have an explicitform,therefore only its function values can be employed in the numerical methods for solv-ing such problems.We study a set of numerical methods that are easily implementable.Each iteration of the proposed methods consists of two procedures.The first(prediction)procedure utilizes alternating projections to produce a predictor.The second(correction)procedure generates the new iterate via some minor computations.Convergence of theproposed methods is proved under mild conditions.Preliminary numerical experiments forsome traffic equilibrium problems illustrate the effectiveness of the proposed methods.     

论求解单调变分不等式的一些投影收缩算法

论求解单调变分不等式的一些投影收缩算法何炳生（南京大学）ＯＮＳＯＭＥＰＲＯＪＥＣＴＩＯＮＡＮＤＣＯＮＴＲＡＣＴＩＯＮＭＥＴＨＯＤＳＦＯＲＳＯＬＶＩＮＧＭＯＮＯＴＯＮＥＶＡＲＩＡＴＩＯＮＡＬＩＮＥＱＵＡＬＩＴＩＥＳ￥ＨｅＢｉｎｇ－ｓｈｅｎｇ（Ｎａｍｉｎ...     

求解广义混合单调变分不等式的预解算子方法

1引言设R~n表示n维欧式空间,‖·‖和＜,＞分别表示R~n中的范数和内积,K为R~n中的非空闭凸集,(?)是R~n到R∪{ ∞)的算子．对于给定的非线性算子T,g：R~n→R~n,考虑下面的广义混合变分不等式,记为GMVI：求u∈R~n满足(Tu)~T(g(v)-g(tu)) (?)(g(v))-(?)(g(u))(?)0,(?)g(v)∈R~n．(1)假如(?)是R~n中非空闭凸集K的指标集,即,(?)(u)≡I_k(u)=(?)．此时GMVI等价于下面的广义变分不等式：求u∈R~n,g(u)∈K满足     

一类拟双线性型变分不等式解的存在性

本文引入和讨论了一类拟双线性型变分不等式解的存在性问题，其结果改进了文［４－６］中的相应结果．     

关于一个非线性变分不等式系统的逼近可解性

本文研究了一个包含两个不同松弛强制映像的非线性变分不等式系统的逼近可解性. 利用数值和逼近的方法, 分析了一个新的迭代序列,改进和推广了近年来的一些最新结果.     

A COMPUTATIONAL APPROACH FOR OPTIMAL CONTROL SYSTEMS GOVERNED BY PARABOLIC VARIATIONAL INEQUALITIES

Iterative techniques for solving optimal control systems governed by parabolic variational inequalities are presented. The techniques we use are based on linear finite elements method to approximate the state equations and nonlinear conjugate gradient methods to solve the discrete optimal control problem. Convergence results and numerical experiments are presented.     

关于一类变分不等式的LQP算法

本文研究一类ξ-单调的变分不等式问题.利用KKT条件将原问题转换为非线性互补问题(nonlinear complementarity problem,NCP)的方法,获得了基于logarithmic-quadratic proximal(LQP)的算法及其改进形式,推广了LQP算法的适用范围.     

无单调性集值变分不等式的一种投影算法

本文给出了求解无单调性集值变分不等式的一个新的投影算法,该算法所产生的迭代序列在Minty变分不等式解集非空且映射满足一定的连续性条件下收敛到解.对比文献[10]中的算法,本文中的算法使用了不同的线性搜索和半空间,在计算本文所引的两个数值例子时,该算法比文献[10]中的算法所需迭代步更少.     

关于单调变分不等式的不精确邻近点算法的收敛性分析

We consider a proximal point algorithm(PPA) for solving monotone variational inequalities. PPA generates a sequence by solving a sequence of strongly monotone subproblems .However,solving the subproblems is either expensive or impossible. Some inexact proximal point algorithms(IPPA) have been developed in many literatures. In this paper, we present a criterion for approximately solving subproblems. It only needs one simple additional work on the basis of original algorithm, and the convergence criterion becomes milder. We show that this method converges globally under new criterion provided that the solution set of the problem is nonempty.     

解变分不等式的一种二次投影迭代算法

本文研究了一类新的求解伪单调变分不等式的二次投影迭代算法.利用Armijo型线性搜寻程序,建立了一类新的超平面,他们严格分离当前迭代点与变分不等式的解集.运用超平面的这种分离性质,在较弱的条件下证明了该算法生成的无穷序列是全局收敛的.数值实验证明该算法是有效的.     

A NEW SELF-ADAPTIVE ITERATIVE METHOD FOR GENERAL MIXED QUASI VARIATIONAL INEQUALITIES

The general mixed quasi variational inequality containing a nonlinear term φ is a useful and an important generalization of variational inequalities. The projection method can not be applied to solve this problem due to the presence of nonlinear term. It is well known that the variational inequalities involving the nonlinear term φ are equivalent to the fixed point problems and resolvent equations. In this article, the authors use these alternative equivalent formulations to suggest and analyze a new self-adaptive iterative method for solving general mixed quasi variational inequalities. Global convergence of the new method is proved. An example is given to illustrate the efficiency of the proposed method.     

变分不等式问题的一个外梯度投影算法

１．引 言 设Ｃ Ｒｎ为非空闭凸集，为连续映射．变分不等式问题，记为ＶＩ（Ｆ，Ｃ），是求满足上述条件的向量ｘ∈Ｃ变分不等式问题在工程力学，交通运输，经济运筹等方面具有广泛的应用并越来越受到人们的重视 ［２，３］ 求解变分不等式问题有很多解法，其中最简单的是投影     

非扩张半群的变分不等式的不动点解的粘性逼近方法

本文研究了非扩张半群的变分不等式的不动点解的迭代算法.利用变分不等式与不动点问题的解的关系,结合粘性逼近方法,建立了非扩张半群的不动点的两步迭代格式,证明了该方法所得到的迭代序列在一定条件下的强收敛性,并收敛于某变分不等式的唯一解.     

BOUNDARY ELEMENT APPROXIMATION OF THE SEMI-DISCRETE PARABOLIC VARIATIONAL INEQUALITIES OF THE SECOND KIND

The boundary element approximation of the parabolic variational inequalities of the second kind is discussed. First, the parabolic variational inequalities of the second kind can be reduced to an elliptic variational inequality by using semidiscretization and implicit method in time; then the existence and uniqueness for the solution of nonlinear non-differentiable mixed variational inequality is discussed. Its corresponding mixed boundary variational inequality and the existence and uniqueness of its solution are yielded. This provides the theoretical basis for using boundary element method to solve the mixed vuriational inequality.     

关于一类变分不等式的迭代算法

本文通过对「１」中相应结构的讨论与改进,利用变分不等式求解技巧,讨论了Ｈｉｌｂｅｒｔ空间中一类广义变分不等式的解的迭代算法及其收敛性,指出了文「１」中主要结果的证明的一些不足之处,本文所得结果推广并改进了「１」的相应结论。     

A NEW SMOOTHING APPROXIMATION METHOD FOR SOLVING BOX CONSTRAINED VARIATIONAL INEQUALITIES

In this paper, we first give a smoothing approximation function of nonsmooth system based on box constrained variational inequalities and then present a new smoothing approximation algorithm. Under suitable conditions,we show that the method is globally and superlinearly convergent. A few numerical results are also reported in the paper.     

求单调变分不等式隐式方法的一个单调下降性质

1　引　　言变分不等式在数学规划中起着很重要的作用 ,许多研究者 [3 ]讨论了这一问题 .对于单调线性变分不等式问题 ,文 [4 -7]提出了几种投影收缩算法 ( PC) .最近文 [7]中研究了如下的一类变分不等式问题( VI)　　 u∈Ω ,　　 ( v -u) TF( u)≥ 0 ,　　 v∈Ω . ( 1 )其中Ω Rn 是一个闭凸集 ,F是 Rn到自身的连续单调映射 ,即F( u) -F( v) T( u -v)≥ 0 ,　　　 u,v∈ Rn. ( 2 )由 [1 ]知 ,对于任意的 β>0 ,变分不等式 ( 1 )等价于投影方程于是求解 ( 1 )即是寻求e( u,β)∶ =u -PΩ[u -βF( u) ]的零点 .本文中 Ω*表示 ( …