紧框架中的Korovkin型定理

关于线性正算子的Korovkin 定理在函数逼近理论中是著名的定理, 本文将建立几个关于紧框架的Korovkin 型定理.     

二元函数空间上线性算子的逼近定理

本文利用Gonska方法,研究二元函数空间上线性算子的逼近性质,建立Korovkin型量化定理及其逆定理.     

一个一般的拓扑型极大极小定理

本文得出一个一般形式的拓扑型的极大极小定理，它包含的主要结果为特例，而且回答了［３］中提出的一个未解决问题。     

Korovkin定理的推广与算子半群的渐近性

空间上的每个一致有界正算子半群的渐近稳定性完全由三个简单函数c,c.id,c.id 2(其中c∈L p为任意一个满足essinf{r∈Ω} c(r)>0的函数,id(r)=r,id 2(r)=r 2,r∈Ω)所决定, 由此, 本文给出了L p上正算子半群渐近稳定的一些新的判别准则.     

Korovkin定理的推广与算子半群的渐近性

本文探讨常致函数在Korovkin定理中的作用,并由此将Korovkin定理由连续函数空间推广到L~p（Ω）空间（其中Ω=[a,b]或（a,b）.这个推广的重要性之一在于:L~p空间上的每个一致有界正算子半群的浙近稳定性完全由三个简单函数c,c·id,c·id~2（其中c∈L~p为任意一个满足essinfc(r)＞0的函数,id（r）-r,id~2(r)=,r∈Ω）所决定,由此,本文绘出了Lp上正算子半群渐近稳定的一些新的判别准则。     

模糊赋范线性空间上的Kakutani不动点定理

在Fuzzy赋范线性空间上引入多值映射的闭性概念与半连续概念,并建立了此空间上的Kakutani不动点定理.     

赋范空间中φ-伪压缩型映象的收敛定理

in this paper,by virtue of an inequality and some analysis techniques,we prove some convergence theorems on the iterative process for nonlinear mappings of Φ-pseudo contractive type in normed linear spaces,which extend and improve the corresponding results obtained by others recently.     

广义凸空间内的KKM型定理和极小极大不等式及鞍点定理

本文在非紧G-凸空间内对具有有限闭值和有限开值的G-KKM,广义G-KKM和广义S-KKM映象建立了某些新的KKM型定理。应用这些KKM型定理,在G-凸空间内得到了新的 Ky Fan型极小极大不等式和鞍点定理。这些结论推广了最近文献中的许多已有结果。     

概率赋范空间上的一些不动点定理的进一步分析

该文在局部有界ＰＮ空间或邻域卜局部凸ＰＮ空间上,证明了非空完备子集上的概率压缩映象必有唯一不动点;并在度量线性空间中给出了关于伪范族一致压缩映象的不动点定理．     

区间空间中的非紧极大极小定理

本文得到了区间空间中两类非紧极大极小定理．其结果不仅包含了引文[1-10]中的相应结果为特例，而且发展和改进了[6]中的相应结果．     

The De Rham Decomposition Theorem For Metric Spaces

We generalize the classical de Rham decomposition theorem for Riemannian manifolds to the setting of geodesic metric spaces of finite dimension. Received: May 2006 Accepted: December 2006     

Korovkin-type theorem and application

Let (L_n) be a sequence of positive linear operators on C[0,1], satisfying that (L_n(e_i)) converge in C[0,1] (not necessarily to e_i) for i=0,1,2, where e_i(x)=xⁱ. We prove that the conditions that (L_n) is monotonicity-preserving, convexity-preserving and variation diminishing do not suffice to insure the convergence of (L_n(f)) for all fC[0,1]. We obtain the Korovkin-type theorem and give quantitative results for the approximation properties of the q-Bernstein operators B_n,q as an application.     

Characterization of the least concave majorant of brownian motion,conditional on a vertex point,with application to construction

The characterization of the least concave majorant of brownian motion by Pitman (1983,Seminar on Stochastic Processes, 1982 (eds. E. Cinlar, K. L. Chung and R. K. Getoor), 219–228, Birkhäuser, Boston) is tweaked, conditional on a vertex point. The joint distribution of this vertex point is derived and is shown to be generated with extreme ease. A procedure is then outlined by which one can construct the least concave majorant of a standard Brownian motion path over any finite, closed subinterval of (0, ∞). This construction is exact in distribution. One can also construct a linearly interpolated version of the Brownian motion path (i.e. we construct the Brownian motion path over a grid of points and linearly interpolate) corresponding to this least concave majorant over the same finite interval. A discussion of how to translate the aforementioned construction to the least concave majorant of a Brownian bridge is also presented.     

Note on a Korovkin-type theorem

A new Korovkin-type theorem and its converse theorem are established. We compare our direct result with the Korovkin-type theorem given by Wang [15]. As applications we obtain quantitative estimates for q  -Bernstein-type operators which preserve the functions _e0(x)=1$e_0(x)=1$ and _ej(x)=x^j$e_j(x)=x^j$.     

关于局部紧度量空间的映象

本文借助于商映射、伪开映射和闭映射建立局部紧度量空间和几类具有某些特定性质mk-系之间的联系，作为推论.得到：双商ss-映射保持局部紧度量空间.     

度量空间和锥度量空间中的若干不动点定理

给出了度量空间和锥度量空间中的若干不动点定理.利用这些不动点定理,统一并推广了度量空间和锥度量空间中的若干经典的不动点定理.     

度量空间中Current的某些特征

作者从代数观念出发研究了Current的表示定理. 对于完备不变Current,利用构建的极小三元组技巧,给出了一个类似的Radon-Nikodym定理.     

The Locally Connected Compact Metric Spaces Embeddable In The Plane

We prove that a 2-connected, locally connected, compact topological space M is homeomorphic to a subset of the 2-sphere if and only if M is metrizable and contains none of the Kuratowski graphs K ₅ and K _3,3.     

Lipschitz曲线上Besov-Triebel-Lizorkin空间的嵌入定理

本文用离散的Calderón型再生公式。证明了Lipschitz曲线上Beasov空间与Triebel-Lizorkin空间的嵌入定理。