Leray-Schauder不动点定理的一个新证明

给出Leray-Schauder不动点定理的一个新证明.我们首先给出集值映射的焊接引理,利用集值映射的焊接引理和Kakutani不动点定理证明Leray-Schauder不动点定理,并证明Leray-Schauder不动点定理与Brouwer不动点定理等价.     

A simple proof of P. Carter's theorem

We give a simple proof of the following result of P. Carter: Given a twist homeomorphism of an annulus with at most one fixed point in the interior of the annulus, then there exists an essential simple closed curve inside this annulus meeting its image in at most the (possible) interior fixed point.

     

A fixed point theorem for the infinite-dimensional simplex

We define the infinite-dimensional simplex to be the closure of the convex hull of the standard basis vectors in R^∞, and prove that this space has the fixed point property: any continuous function from the space into itself has a fixed point. Our proof is constructive, in the sense that it can be used to find an approximate fixed point; the proof relies on elementary analysis and Sperner's lemma. The fixed point theorem is shown to imply Schauder's fixed point theorem on infinite-dimensional compact convex subsets of normed spaces.     

COMPARISON THEOREMS TO BOUNDARY VALUE PROBLEMS FOR ORDINARY DIFFERENTIAL EQUATIONS

ＣＯＭＰＡＲＩＳＯＮＴＨＥＯＲＥＭＳＴＯＢＯＵＮＤＡＲＹＶＡＬＵＥＰＲＯＢＬＥＭＳＦＯＲＯＲＤＩＮＡＲＹＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮＳ￥ＬＩＹＯＮＧ；ＷＡＮＧＨＵＡＩＺＨＯＮＧＡｂｓｔｒａｃｔ：Ａｕｎｉｆｉｅｄａｐｐｒｏａｃｈｉｓｇｉｖｅ...     

Bolzano's Theorems for Holomorphic Mappings

The existence of a zero for a holomorphic functions on a ball or on a rectangle under some sign conditions on the boundary generalizing Bolzano's ones for real functions on an interval is deduced in a very simple way from Cauchy's theorem for holomorphic functions.A more complicated proof,using Cauchy's argument principle,provides uniqueness of the zero,when the sign conditions on the boundary are strict.Applications are given to corresponding Brouwer fixed point theorems for holomorphic functions.Extensions to holomorphic mappings from Cn to Cn are obtained using Brouwer degree.     

The brouwer fixed point theorem and tetragon with all vertexes in a surface

LetD be a disc with radiusr in the Euclidean plane ℝ², and letF be a Lipschitz continuous real valued function onD. SupposeA ₁ A ₂₁ A ₃ A ₄ is an isosceles trapezoid with lengths of edges not greater thanr, and ∠A ₁ A ₂₁ A ₃ = α≤π/2 By means of the Brouwer fixed point theorem, it is proved that ifF has a Lipschitz constant λ≤min{1, tgα}, then there exist four coplanar points in the surfaceM = {(x, y, F(x, y))∈ℝ³:(x, y)ℝ} which span a tetragon congruent toA ₁ A ₂₁ A ₃ A ₄. In addition, some further problems are discussed. Project supported by the National Natural Science Foundation of China (Grant No. 19231201).     

Generalized nonlinear models of suspension bridges

This paper generalizes some results established in [J. Malík, Nonlinear models of suspension bridges, J. Math. Anal. Appl., in press]. The geometric nonlinearity connected with the torsion of a road bed is included in the generalized model. The basic variational equations are derived from the principle of minimum energy. The existence of a solution to the generalized problem is proved. The existence is based on the Brouwer fixed-point theorem.     

Free lines for homeomorphisms of the open annulus

Let be a homeomorphism of the open annulus isotopic to the identity and let be a lift of to the universal cover without fixed point. Then we show that admits a Brouwer line which is a lift of a properly imbedded line joining one end to the other in the annulus or admits a free essential simple closed curve.

     

集值映象重合点定理的进一步改进和推广

本文是文［１］的继续．在更一般的条件下，研究了完备度量空间中集值映象的重合点和不动点存在性问题     

两点边值问题解的存在性

本文讨论两点边值问题解的存在性,在没有孤立性条件下,获得了不动点定理,作为应用实例,给出了反应扩散方程稳态解的存在性证明。     

Existence of Solutions of Generalized Vector Variational Inequalities in Reflexive Banach Spaces

The purpose of this paper is to study the solvability for a class of generalized vector variational inequalities in reflexive Banach spaces. Utilizing the KKM-Fan lemma and the Nadler’s result, we prove the solvability results for this class of generalized vector variational inequalities for monotone vector multifuctions. On the other hand, we first introduce the concepts of complete semicontinuity and strong semicontinuity for vector multifunctions. Then we prove the solvability for this class of generalized vector variational inequalities without monotonicity assumption by using these concepts and by applying the Brouwer fixed point theorem. The results in this paper are extension and improvement of the corresponding results in Huang and Fang (2006).     

一类具p-laplacian算子的含积分边界条件的分数阶微分方程边值问题解的存在性

利用Green函数的性质、u_0-边界函数、不动点指数定理及锥压缩与锥拉升不动点定理,研究一类具p-laplacian算子的含积分边界条件的微分方程边值问题解的存在性.     

An application of Ramsey's Theorem to the Banach Contraction Principle

One of the most fundamental fixed-point theorems is Banach's Contraction Principle, of which the following conjecture is a generalization.

Generalized Banach Contraction Conjecture (GBCC). Let be a self-map of a complete metric space , and let . Let be a positive integer. Assume that for each pair , . Then has a fixed point.

Unlike Banach's original theorem (the case ), the above hypothesis does not compel to be continuous. In this paper we use Ramsey's Theorem from combinatorics to establish the GBCC for arbitrary in the case when is assumed to be continuous, and also derive a result which enables us to prove the GBCC when without the assumption of continuity; it is known that the case includes instances where is not continuous.

     

拟线性滞后型微分方程正解的存在性

本文研究了下面这种拟线性滞后型微分方程(g(u′)′+a(t) f (ut) =0 ,　　 0 1 ,满足非线性边界条件 .并且通过应用锥不动定理与阿尔采拉 -阿斯卡里定理 ,证明了上述方程至少存在一个正解 .     

一类二阶三点非齐次边值问题正解的存在性

本文讨论了一类二阶三点非齐次边值问题正解的存在性。利用Schander不动点定理，得到了正解的一个存在性结果     

Existence of Nondecreasing and Continuous Solutions of an Integral Equation with Linear Modification of the Argument

We use a technique associated with measures of noncompactness to prove the existence of nondecreasing solutions to an integral equation with linear modification of the argument in the space C[0, 1]. In the last thirty years there has been a great deal of work in the field of differential equations with a modified argument. A special class is represented by the differential equation with affine modification of the argument which can be delay differential equations or differential equations with linear modifications of the argument. In this case we study the following integral equation x（t） = a（t） ＋ （Tx）（t） ∫0^σ（t） u（t, s, x（s）, x（λs））ds 0 〈 λ 〈 1 which can be considered in connection with the following Cauchy problem x＇（t） = u（t, s, x（t）, x（λt））, t ∈ [0, 1], 0 〈 λ 〈 1 x（0） = u0.     

广义Volterra积分方程解的存在性

本文考虑Ｂａｎａｃｈ空间是形如ｘ（ｔ）＝ｕ（ｔ）＋∫_Gtf(t,s,x(s))ds的广义Ｖｏｌｔｅｒｒａ积分方程，利用Ｍ?ｎｃｈ不动点定理得到所论方程解的某些存在定理．     

区间上一类连续自映射的单调迭代根

设Ｉ＝［０,１］,０＜ａ＜ｂ＜１,记Φ_ab≡｛Ｆ∈Ｃ^０（Ｉ）：Ｆ｜［０,ａ］和Ｆ｜［ｂ,１］严格单调递增且Ｆ在［ａ,ｂ］恒取常值｝．本文讨论了Ｆ∈Φ_ab有单调迭代根的充要条件．