共查询到20条相似文献,搜索用时 593 毫秒
1.
We prove that a locally compact ANR-space X is a Q-manifold if and only if it has the Disjoint Disk Property (DDP), all points of X are homological Z
∞-points and X has the countable-dimensional approximation property (cd-AP), which means that each map f: K → X of a compact polyhedron can be approximated by a map with the countable-dimensional image. As an application we prove that
a space X with DDP and cd-AP is a Q-manifold if some finite power of X is a Q-manifold. If some finite power of a space X with cd-AP is a Q-manifold, then X
2 and X × [0, 1] are Q-manifolds as well. We construct a countable family χ of spaces with DDP and cd-AP such that no space X ∈ χ is homeomorphic to the Hilbert cube Q whereas the product X × Y of any different spaces X, Y ∈ χ is homeomorphic to Q. We also show that no uncountable family χ with such properties exists.
This work was supported by the Slovenian-Ukrainian (Grant No. SLO-UKR 04-06/07) 相似文献
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In this note,we present that:(1)Let X=σ{Xα:α∈A} be|A|-paracompact (resp.,hereditarily |A|-paracompact).If every finite subproduct of {Xα:α∈A} has property b1 (resp.,hereditarily property b1),then so is X.(2) Let X be a P-space and Y a metric space.Then,X×Y has property b1 iff X has property b1.(3) Let X be a strongly zero-dimensional and compact space.Then,X×Y has property b1 iff Y has property b1. 相似文献
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Banach空间中不适定线性算子方程的最佳逼近解 总被引:1,自引:0,他引:1
设X,Y为Banach空间,T为从X到Y的线性算子.T的值域R(T)≠Y且为逼近紧子空间,T的零空间N(T)≠{θ}.证得不适定算子方程Tx=y的最佳逼近解对任意y∈Y均存在的充分必要条件是N(T)为X的迫近子空间. 相似文献
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Let X be a topological space and let Φ ? C(X). Then there exists a topological space Y containing X as a subspace and such that Φ = C(Y)¦X, if and only if Φ is weakly composition closed, i.e., for any index set I, any fi ∈ Φ (i ∈ I) and any continuous map k : RI → Rwe have k ° 〈fi〉 ∈ Φ, where 〈fi〉 : X → RI is the map with i-th coordinate fi. The analogous statement is valid for functions to any T1 space, rather than to R, and even we can consider functions to any set of T1 spaces, and then a generalization of the above statement is valid, with a suitably defined weak composition closedness property. We also show that some earlier results on characterization of function classes Φ ? C(X) of the form C(Y)¦X, with Y some extension of a given topological space X, and on the characterization of function classes C(〈X, T〉), with T some topology on a given set X, respectively, can be generalized in an analogous way as above, by means of composition properties analogous to the above one or by filter closedness (for functions to any set of T3 spaces, or to any set of topological spaces, respectively). 相似文献
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考虑如下的参数向量优化问题minK{f(w,x)|x∈X,g(w,x)∈C},这里f:W×X→Y是从赋范空间W和X的积到另一个赋范空间Y的Hadamard可微的单值映射,K Y是一个尖闭凸锥,C是Banach空间Z中的一个尖闭凸锥,g:W×X→Z是一个Fréchet可微的映射.借助目标函数的导数、约束映射的余切导数及拉格朗日映射给出了值映射的余切上图导数的两个表示. 相似文献
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设X和Y是赋范空间,如果映射f:X→Y满足{||f(x)+f(y)||,||f(x)-f(y)||}={||x+y||,||x-y||}(x,y∈X),则称f是一个相位等距算子.设g,f:X→Y是映射,若存在相位函数ε:X→{-1,1},使得ε·f=g,则称g和f是相位等价的.本文将证明改进的Tsirelson空间TM上的任意满相位等距算子均相位等价于一个线性等距算子.该结论同时也给出了改进的Tsirelson空间TM上的Wigner型定理. 相似文献
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This paper considers the graph sequence graph (f^n )={x×f^n : x ∈X} of the iterates f^n of a continuous map f : X →X on a compact metric space (X, d). The main aim is to introduce serval limit sets by using different recurrent time sets, and discuss the relation between dynamics of the underlying compact system (X, f) and the structure of these limit sets, from a topological or fractal viewpoint. 相似文献
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令(X,d)是紧的度量空间,用↓USC(X)和↓LIP(X)分别表示从X到I所有的上半连续映射和所有Lipschitz映射的下方图形的全体.本文证明如果X是一个无限的紧的度量空间,则(↓USC(X),↓LIP(X))≈(Q,B(Q)),其中B(Q)=Q\(-1,1)~ω是Hilbert立方体Q=[-1,1]~ω的伪边界. 相似文献
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We investigate certain geometric properties of the spaces of idempotent measures. In particular, we prove that the space of idempotent measures on an infinite compact metric space is homeomorphic to the Hilbert cube. 相似文献
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Siberian Mathematical Journal - Let X be a Banach space and let T: X → X be a linear power bounded operator. Put X 0 = {x ∈ X | T n x → 0}. We prove that if X 0 ≠ X then... 相似文献
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In this paper we show that certain actions are the a-homomorphic images of actions with disjoint maximal orbits. We also show
that if T is a compact semigroup acting on a compact space X, then there is a compact right trivial semigroup Y and a congruenceN of T×Y such that (T×Y)/N homeomorphic to X and the action T×X→X is isomorphic the action of T on (T×Y)/N. 相似文献
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Kenneth Kunen 《Topology and its Applications》2009,156(7):1199-1215
We consider the Complex Stone-Weierstrass Property (CSWP), which is the complex version of the Stone-Weierstrass Theorem. If X is a compact subspace of a product of three linearly ordered spaces, then X has the CSWP if and only if X has no subspace homeomorphic to the Cantor set. In addition, every finite power of the double arrow space has the CSWP. These results are proved using some results about those compact Hausdorff spaces which have scattered-to-one maps onto compact metric spaces. 相似文献
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Let X,Y be Banach spaces.We prove that if their unit spheres S(X)and S(Y)are(α,β)-H?lder homeomorphic for some α,β ∈(0,1].Then the unit spheres of Lp(Ω,μ,X)and ... 相似文献
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ImagesandPreimagesofD_0Spaces¥DaiMumin;ChenHaiyan(DepartmentofMath.andInformationScience,UniversityofGuangxi)Abstract:Thispep?.. 相似文献
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H. Mohebi A. M. Rubinov 《分析论及其应用》2006,22(1):20-40
We develop a theory of downward sets for a class of normed ordered spaces. We study best approximation in a normed ordered space X by elements of downward sets, and give necessary and sufficient conditions for any element of best approximation by a closed downward subset of X. We also characterize strictly downward subsets of X, and prove that a downward subset of X is strictly downward if and only if each its boundary point is Chebyshev. The results obtained are used for examination of some Chebyshev pairs (W,x), where ∈ X and W is a closed downward subset of X 相似文献
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T为紧致度量空间X上的连续映射,M(X)为X上所有Borel概率测度.设x∈X,记Mx(T)为概率测度序列{1n∑n 1i=0δTi(x)}在M(X)中的极限点的集合,其中δx表示支撑集是{x}的点测度.记W(T)和QW(T)分别为T的弱几乎周期点和拟弱几乎周期点集.本文证明,如果(X,T)非平凡且满足specifcation性质,则存在x,y∈QW(T)/W(T)(称为真拟弱几乎周期点),分别满足μ∈Mx(T),x∈Supp(μ)和ν∈My(T),y∈/Supp(ν),回答了周作领等提出的公开问题.Mx(T)在弱拓扑中是紧致连通集,所以,要么是单点集,要么是不可数集.如果x∈QW(T)/W(T),则Mx(T)是不可数集.一个自然的问题是,怎么刻画M x(T)是单点集的点x(这时x称为拟正则点).本文给出M x(T)是单点集的充要条件. 相似文献
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D. N. Georgiou S. D. Iliadis B. K. Papadopoulos 《Journal of Mathematical Sciences》1996,81(2):2506-2514
In the present paper we introduce notions of A-splitting and A-jointly continuous topology on the set C(Y,Z) of all continuous
maps of a topological space Y into a topological space Z, where A is any family of spaces. These notions satisfy the basic
properties of splitting and jointly continuous topologies on C(Y,Z). In particular, for every A, the greatest A-splitting
topology on C(Y,Z) (denoted by τ(A) always exists. We indicate some families A of spaces for which the topology τ(A) coincides
with the greatest splitting topology on C(X,Y). We give a notion of equivalent families of spaces and try to find a “simple”
family which is equivalent to a given family. In particular, we prove that every family is equivalent to a family consisting
of one space, and the family of all spaces is equivalent to a family of all T1-spaces containing at most one nonisolated point. We compare the topologies τ({X}) for distinct compact metrizable spaces
X and give some examples. Bibliography: 13 titles.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 208, 1993, pp. 82–97.
Translated by A. A. Ivanov. 相似文献
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We prove that a topological space is uniform Eberlein compact iff it is homeomorphic to a super weakly compact subset C of a Banach space such that the closed convex hull coC of C is super weakly compact. We also show that a Banach space X is super weakly compactly generated iff the dual unit ball BX* of X* in its weak star topology is affinely homeomorphic to a super weakly compactly convex subset of a Banach space. 相似文献