连续树映射非游荡集的拓扑结构

本文研究树（即不含有圈的一维紧致连通的分支流形）上连续自映射的非游荡集的拓扑结构．证明了孤立的周期点都是孤立的非游荡点；具有无限轨道的非游荡点集的聚点都是周期点集的二阶聚点，以及ω－极限集的导集等于周期点集的导集和非游荡集的二阶导集等于周期点集的二阶导集．     

N指标d维广义Wiener过程象集代数和性质

令Ｗ↑￣（ｔ）：Ｒ＋＾Ｎ→Ｒ＾ｄ是Ｎ指标ｄ维广义Ｗｉｅｎｅｒ过程，对任意紧集Ｅ，Ｆ∩→Ｒ＋＾Ｎ／｛０｝，本文研究了代数和Ｗ↑￣（Ｅ）－Ｗ↑￣（Ｆ）的Ｈａｕｓｄｏｒｆｆ维数及内点存在性，此结果包含并推广了Ｂｒｏｗｎｉａｎ Ｓｈｅｅｔ的结果。     

关于有效点集的闭性和连通性

本文的主要结果是，假设Ａ是局部凸空间里的紧的Ｆ一集，则Ａ的有效点集Ｅ（Ａ｜Ｃ）是闭集。需要提及的是，此结果中关于Ａ并没有作任何凸性的假设，如果对它再附加某种凸性假设条件时，则本文进一步证明了有效点集Ｅ（Ａ｜Ｃ）不但是闭集，而且还是连通集。     

度量空间中有限点集的费马点

本文首先对紧致的度量拓扑空间证明了有限点集的费马点是存在的，其次，运用度量几何的经典方法考察了度量空间（包括双曲空间和Ｂａｎａｃｈ空间）中有限点集的费马点的唯一性，此外，还对ｎ维欧氏空间Ｅ＾ｎ中有限点集的费马作了进一步研究。     

点集Bézier曲线

提出了点集Bézier曲线的概念,给出了点集Bézier曲线的性质及细分算法.按照点集算术的定义,当点集是长方形闭域或圆盘时,点集Bézier曲线就是区间Bézier曲线或圆盘Bézier曲线,因此,点集Bézier曲线是对区间Bézier曲线和圆盘Bézier曲线的推广.     

N指示d维广义Wiener过程象集内点存在性

令Ｗ＾￣（ｔ）：ＩＲ＋＾Ｎ→ＩＲ＾ｄ是Ｎ指标ｄ维广义Ｗｉｅｎｅｒ过程，对任意紧集Ｅ＝ＩＲ＋＾Ｎ／（０），如果ｄｉｍＥ〉βｄ／２，那么，Ｗ＾￣（Ｅ）几乎处处存在内点，Ｂｒｏｗｎｉａｎ Ｓｈｅｅｔ为特例。     

导集运算及其条件的独立性

对点集拓扑学中由导集运算决定拓扑的方法进行了讨论,给出了导集运算的定义,导集运算决定拓扑定理,并讨论了导集运算中条件的相互独立性.进一步完善了点集拓扑学中有关导集概念的内容.     

约束四点集的最短网络问题

设Ｌ为Ｅｕｃｌｉｄｅａｎ平面上一连续曲线,在Ｌ的一侧有一个含ｎ个固定点的集合Ｎ,且点集Ｎ的凸包ＣＨ（Ｎ）与曲线ＬＩ 相交,总是是在Ｌ上找一点Ｐ,使点集Ｎ∪（Ｐ）的互联网络最短,本文在Ｌ是圆及点集Ｎ含有３个点的条件下给出了问题解。     

三角形欧拉圆的高维推广

采用笛卡儿直角坐标法,定义了高维共球有限点集的"欧拉超球面"(它是三角形欧拉圆的高维推广)、"2号心"等概念,并揭示了它们的一系列基本性质.     

Rasche方法在偏序集上最优集止问题中的应用

本用Ｒａｓｃｈｅ方法对偏序集Ｓ中的点进行了筛选，筛选算法简单明了。设Ｂ（Ｅ）记筛选后的点集，我们证明了１）Ｖ＝ｓｕｐ ＥＸｒ＝ｓｕｐ｛ＥＸτ：τ∈Ｂ（Ｅ）｝；２）若最优停点存在，则必几乎处处取值于Ｂ（Ｅ）中。     

Numerical Experiments with an Interior-Exterior Point Method for Nonlinear Programming

The paper presents an algorithm for solving nonlinear programming problems. The algorithm is based on the combination of interior and exterior point methods. The latter is also known as the primal-dual nonlinear rescaling method. The paper shows that in certain cases when the interior point method (IPM) fails to achieve the solution with the high level of accuracy, the use of the exterior point method (EPM) can remedy this situation. The result is demonstrated by solving problems from COPS and CUTE problem sets using nonlinear programming solver LOQO that is modified to include the exterior point method subroutine.     

Virtually stable maps and their fixed point sets

We introduce the concept of virtually stable selfmaps of Hausdorff spaces, which generalizes virtually nonexpansive selfmaps of metric spaces introduced in the previous work by the first author, and explore various properties of their convergence sets and fixed point sets. We also prove that the fixed point set of a virtually stable selfmap satisfying a certain kind of homogeneity is always star-convex.     

Existence,compactness, and connectedness of solution sets to nonlocal and impulsive Cauchy problems

In this paper, by using some well-known inequalities and Schaefer fixed point theorem, we show existence results for impulsive Cauchy problems with nonlocal conditions. The compactness of solution sets can be shown in some certain conditions. Moreover, connectedness of solution sets to impulsive Cauchy problems is shown.     

Fixed point sets of deformations of polyhedra with local cut points

A locally finite simplicial complex is said to be 2-dimensionally connected if is connected. Such spaces exhibit ``classical' behavior in that they all admit deformations with one fixed point, and they admit fixed point free deformations if and only if the Euler characteristic is zero. A result of G.-H. Shi implies that, for non 2-dimensionally connected spaces, the fixed point sets of deformations are equivalent to the fixed point sets of certain combinatorial maps which he calls good displacements. U. K. Scholz combined Shi's results with a theorem of P. Hall to obtain a characterization of all finite simplicial complexes which admit fixed point free deformations. In this paper we begin by explicitly capturing the combinatorial structure of a non 2-dimensionally connected polyhedron in a bipartite graph. We then apply an extended version of Hall's theorem to this graph to get a realization theorem which gives necessary and sufficient conditions for the existence of a deformation with a prescribed finite fixed point set. Scholz's result, and a characterization of all finite simplicial complexes without fixed point free deformations that admit deformations with a single fixed point follow immediately from this realization theorem.

     

Existence and compactness of solutions to impulsive differential equations with nonlocal conditions

The new type of nonlinear integral inequalities of Volterra–Fredholm type for discontinuous functions is investigated. Then, by using these inequalities and Schaefer fixed‐point theorem, we present new existence results for impulsive semilinear differential equations with nonlocal conditions. Moreover, the compactness of solution sets can be shown in some certain conditions. Copyright © 2015 John Wiley & Sons, Ltd.     

A Continuation Method for Solving Fixed Point Problems in Unbounded Convex Sets

In this paper, an unbounded condition is presented, under which we are able to utilize the interior point homotopy method to solve the Brouwer fixed point problem on unbounded sets. Two numerical examples in R3 are presented to illustrate the results in this paper.     

Generalizations of fixed point theorems and computation

As a powerful mechanism, fixed point theorems have many applications in mathematical and economic analysis. In this paper, the well-known Brouwer fixed point theorem and Kakutani fixed point theorem are generalized to a class of nonconvex sets and a globally convergent homotopy method is developed for computing fixed points on this class of nonconvex sets.     

Three-term conjugate gradient method for the convex optimization problem over the fixed point set of a nonexpansive mapping

Many constrained sets in problems such as signal processing and optimal control can be represented as a fixed point set of a certain nonexpansive mapping, and a number of iterative algorithms have been presented for solving a convex optimization problem over a fixed point set. This paper presents a novel gradient method with a three-term conjugate gradient direction that is used to accelerate conjugate gradient methods for solving unconstrained optimization problems. It is guaranteed that the algorithm strongly converges to the solution to the problem under the standard assumptions. Numerical comparisons with the existing gradient methods demonstrate the effectiveness and fast convergence of this algorithm.     

Chern and Pontryagin Numbers in Perfect Symmetries of Spheres

The paper presents a procedure for constructing smooth actions of finite perfect groups on spheres with fixed point sets having certain prescribed properties (Theorem A); in particular, having any prescribed configuration of Chern and Pontryagin numbers (Corollary C). The main ingredients used are equivariant thickening and equivariant surgery.