Chebyshev-Secant-type Methods for Non-differentiable Operators

In this paper we give a semilocal convergence theorem for a family of iterative methods for solving nonlinear equations defined between two Banach spaces. This family is obtained as a combination of the well known Secant method and Chebyshev method. We give a very general convergence result that allow the application of these methods to non-differentiable problems.     

正规函数与正规族

研究了正规函数与正规族之间的联系,利用分担集合的方法得到一族满足特殊性质p的正规函数,同时利用分担值的方法得到了一个较已有结论更为一般的结果。     

A hybrid projective method for solving system of equilibrium problems with demicontractive mappings applicable in image restoration problems

In this paper, we propose a general iterative scheme based on CQ projection method for finding a common solution of system of equilibrium problems and the fixed point set of a finite family of demicontractive mappings. We also prove strong convergence of the scheme to a common element of the two above-described sets. We then give a numerical example to justify our main result. An example is given in an infinite dimensional space for supporting our main result. Moreover, we apply our main result to solve the unconstrained image restoration problems with a finite family of blurring operators. Our results extend and improve some existing results in the literature.     

用矩匹配方法计算非线性风险度

矩匹配方法是用来求解非线性风险度(Value at Risk，简称：VaR)的一种普遍性方法，它是先假定样本经验分布服从已知分布族，然后运用矩匹配估计方法估计相应的参数，得到资产回报样本的密度函数，再计算风险度VaR；本采用的Johnson分布族是矩匹配方法的直接应用，并且计算出来的结果与局部Monte．Carlo结果进行了比较。并通过实证分析认为这种方法是一种良好的计算非线性VaR方法。     

差商变尺度法的整体收敛性

对于求解无约束最优化问题,变尺度法被公认为是最有效的方法之一,从1971年Powell的开创性工作以来,关于变尺度法收敛性的研究已形成了系统的理论,由于精确导数难以得到,常用差商代替,称为差商变尺度法,对其收敛性理论的研究,尚相当薄弱,本文证明了差商变尺度法的整体收敛性,同时给出了保证收敛的差商步长条件。     

Note – Uncrossing a Family of Set-Pairs

Frank and Jordán [1] proved an important min-max result on covering a crossing family of set-pairs. As an application, among others they can solve the unweighted node-connectivity augmentation problem for directed graphs in polynomial time. In this paper, we show how to solve the dual packing problem in polynomial time. To decompose a fractional dual optimum as a convex combination of integer vertices, besides the ellipsoid method, we use a polynomial-time algorithm for uncrossing a family of set-pairs. Our main result is this uncrossing algorithm. Received November 9, 1998 / Revised October 18, 1999     

广义Baskakov型算子的强逆不等式

利用二阶Ditzian-Totik模考虑一类算子的强逆不等式，这类不等式曾经被许多者用不同的方法研究过。本文将采用一种统一的方法来处理一大类算子的强逆不等式，得到了它们的Ditzian-Ivanov结果。本方法适用于更广的算子。     

Convergence and spectral analysis of the Frontini-Sormani family of multipoint third order methods from quadrature rule

Point of attraction theory is an important tool to analyze the local convergence of iterative methods for solving systems of nonlinear equations. In this work, we prove a generalized form of Ortega-Rheinbolt result based on point of attraction theory. The new result guarantees that the solution of the nonlinear system is a point of attraction of iterative scheme, especially multipoint iterations. We then apply it to study the attraction theorem of the Frontini-Sormani family of multipoint third order methods from Quadrature Rule. Error estimates are given and compared with existing ones. We also obtain the radius of convergence of the special members of the family. Two numerical examples are provided to illustrate the theory. Further, a spectral analysis of the Discrete Fourier Transform of the numerical errors is conducted in order to find the best method of the family. The convergence and the spectral analysis of a multistep version of one of the special member of the family are studied.     

亚纯函数族的一个正规定则

本文研究了涉及一类微分多项式的亚纯函数族的正规性问题.利用Zalcman-Pang的方法,得到一个正规定则,推广了2011年袁文俊等得到的结果.     

Iterative approaches to solving convex minimization problems and fixed point problems in complete CAT(0) spaces

In this paper, we propose a new modified proximal point algorithm for finding a common element of the set of common minimizers of a finite family of convex and lower semi-continuous functions and the set of common fixed points of a finite family of nonexpansive mappings in complete CAT(0) spaces, and prove some convergence theorems of the proposed algorithm under suitable conditions. A numerical example is presented to illustrate the proposed method and convergence result. Our results improve and extend the corresponding results existing in the literature.     

Hilbert空间上依范连续的α-次预解算子族

主要运用Laplace-Stieltjes的方法,讨论Hilbert空间上α-次预解算子族的依范连续性与其预解式的关系,得到一个主要结果：Hilbert空间上α-次预解算子族的依范连续性与其预解式在当｜τ｜→∞时,‖（ω＋iτ）~（α-1）R（（ω＋iτ）~α,A）‖→0等价.     

关于ff^（（k））的正规定则

研究了一类微分多项式的正规性问题,利用分担值的方法得到了一个比已有结论更一般性的结果.     

Homogenization of hyperbolic damped stochastic wave equations

For a family of linear hyperbolic damped stochastic wave equations with rapidly oscillating coefficients, we establish the homogenization result by using the sigma-convergence method. This is achieved under an abstract assumption covering special cases like the periodicity, the almost periodicity and some others.     

A hybrid method for a family of relatively quasi-nonexpansive mappings and an equilibrium problem in Banach spaces

We introduce a hybrid method for finding a common element in the solutions set of an equilibrium problem and the common fixed points set of a countable family of relatively quasi-nonexpansive mappings in a Banach space. A strong convergence theorem of the proposed method is established by using the concept of the Mosco convergence when the family {T _n } satisfies the (*)-condition. The examples of three generated mappings which satisfy the (*)-condition are also given. Using the obtained result, we give some applications concerning the variational inequality problem and the convex minimization problem.     

A simple method and its applications to nonlinear partial differential equations

In this paper, a simple method is proposed for constructing more general exact solutions of nonlinear partial differential equations. We choose the Camassa and Holm-Degasperis and Procesi equation and the generalized b family equations to illustrate the validity and advantages of the method. As a result, many new and more general exact solutions are obtained. Some previous results are extended.     

On the unique solvability of a family of two-point boundary-value problems for systems of ordinary differential equations

We consider a family of two-point boundary-value problems for systems of ordinary differential equations with functional parameters. This family is the result of the reduction of a boundary-value problem with nonlocal condition for a system of second-order, quasilinear hyperbolic equations by the introduction of additional functions. Using the parametrization method, we establish necessary and sufficient conditions of the unique solvability of the family of two-point boundary-value problems for a linear system in terms of the initial data. We also prove sufficient conditions of the unique solvability of the problem considered and propose an algorithm for its solution. __________ Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 12, No. 4, pp. 21–39, 2006.     

涉及微分多项式的亚纯函数的正规族

本文通过研究亚纯函数的正规族.利用反证法,获得了一个与分担值有关的涉及微分多项式的一般性的正规定则,改进了方明亮和L.Zalcman在2002年得到的一个结果.     

A weighted averaging method for treating discontinuous spectral data

We introduce a weighted averaging method for improving the inevitable error induced by the Gibbs phenomenon appearing in a spectral approximation for a discontinuous function. In the result we have a family of filters generalizing the well known Fejer filter. In addition, for high resolution recovery, we propose an adaptive filter which is competitive with the existing exponentially convergent adaptive filter. Several numerical examples are included to show the applicability of the method presented.     

Constraining by a family of strictly nonexpansive idempotent functions with applications in image reconstruction

When solving an image reconstruction problem a previous knowledge concerning the original image may lead to various constraining strategies. A convergence result has been previously proved for a constrained version of the Kaczmarz projection algorithm with a single strictly nonexpansive idempotent function with a closed image. In this paper we consider a more general projection based iterative method and a family of such constraining functions with some additional hypotheses in order to better use the a priori information for every approximation calculated. We present a particular family of box-constraining functions which satisfies our assumptions and we design an adaptive algorithm that uses an iteration-dependent family of constraining functions for some numerical experiments of image reconstruction on Tomographic Particle Image Velocimetry.     

Convergence analysis of the high-order mimetic finite difference method

We prove second-order convergence of the conservative variable and its flux in the high-order MFD method. The convergence results are proved for unstructured polyhedral meshes and full tensor diffusion coefficients. For the case of non-constant coefficients, we also develop a new family of high-order MFD methods. Theoretical result are confirmed through numerical experiments.