共查询到19条相似文献,搜索用时 46 毫秒
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This paper proves the following results: Let X = lim← { Xσ,π^σρ,∧ },| ∧ | =λ, and every pro-jection πσ : X → Xσ be an open and onto mapping. (A) If X is λ-paracompact and every Xσ is normal and δθ-refinable, then X is normal and δθ-refinable; (B) If X is hereditarily λ-pamcompact and every Xσ is hereditarily normal and hereditarily δθ-refinable, then X is hereditarily normal and hereditarily δθ-refiable. 相似文献
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本文给出了空间为D-空间的-充分条件,主要结论如下:如果空间X有一点可数族F,满足对X的任-子集A (C) X,若A在X中不闭,都存在某点x ∈-A\A,使得对X的任一开集U,若X∈U,都存在某个F∈F,使得X ∈F(C) U且F ∩ A≠ (θ),则X是D-空间.由此结论,我们得到-序列空间若有点可数cs*-网络,则X是D-空间. 相似文献
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本文给出了空间为D-空间的一充分条件,主要结论如下:如果空间X有一点可数族厂,满足对X的任一子集A X,若A在X中不闭,都存在某点X∈A\A,使得对X的任一开集U,若X∈U,都存在某个F∈F,使得X∈F U且F∩A≠D,则X是D-空间.由此结论,我们得到一序列空间若有点可数C8^8-网络,则X是D-空间. 相似文献
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关于弱MCP空间与弱层空间 总被引:1,自引:0,他引:1
本文引入了与已知的一些空间类非常类似的两个概念,我们分别称它们为弱MCP空间与弱层空间.本文主要讨论了这两空间类的等价命题与一些基本性质,及它们与原有空间类的关系. 相似文献
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研究了锥意义下的半预不变凸性的新性质.首先,对彭再云等的文献(彭再云,李科科,唐平,黄应全.向量值D-半预不变真拟凸映射的判定与性质[J].重庆师范大学学报(自然科学版),2014,31(5):18-25.)中的例4进行了修正,使其满足条件E.然后,给出了条件E1的一个重要性质,并在此基础上结合稠密性结果,分别利用D-半严格半预不变真拟凸性和D-严格半预不变真拟凸性建立了D-半预不变凸性的刻画.最后利用D-半预不变真拟凸性给出了D-半预不变凸性的刻画. 相似文献
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本文研究了强α空间在有限到一的闭映射下的映射性质问题.利用闭映射的等价刻画构造g函数,获得了强α空间在有限到一的闭映射下保持的结果,改进了强α空间在有限到一的既开又闭映射下保持的结果.本文还研究了σ空间的半层对应刻画. 相似文献
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The basic theorem presented shows that the product of a linearly ordered space and a countable (regular) space is normal. We prove that the countable space can be replaced by any of a rather large class of countably tight spaces. Examples are given to prove that monotone normality cannot replace linearly ordered in the base theorem. However, it is shown that the product of a monotonically normal space and a monotonically normal countable space is normal.
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We prove that every neighborhood assignment for a monotonically normal space has a kernel which is homeomorphic to some subspace of an ordinal. As a corollary, every monotone neighborhood assignment for a monotonically normal space has a discrete kernel, which gives a partial answer to a question posed in Buzyakova et al. (2007) [5]. We also give an example of a regular space which has a neighborhood assignment with no kernels homeomorphic to any subspace of an ordinal. 相似文献
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赵斌 《高校应用数学学报(英文版)》2005,20(4)
§1Introduction Theclassofstratifiable(=M3)spacesincludesallmetricspacesandmanytopological groups.Stratifiablespaceholdsmostofthestrongestandusefulpropertiesofmetric space.ThequestionproposedbyCederwhetherstratifiablespaceisM1spaceornotisstill opennow.ManyresearcheshavediscussedthepropertiesofMi(i=1,2,3)spacesthrough monotonenormality(see[2-7]).Borges[6]studiedthemonotonicallynormalproperties,Heath,etal.[5]gavemajorcontributiononmonotonenormality,andBuck,etal.[2]proposedseveraladditionalcha… 相似文献
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Zhao Bin 《高校应用数学学报(英文版)》2005,20(4):469-474
This paper investigates Buck's question about which class of spaces is strongly monotonically T2,and if other properties are combined with strongly monotonically T2,which class of spaces could be got. Based on having a cushioned pair-base space and compact strongly monotonically T2 space,some results (Theorems 1--3) are obtained. 相似文献
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葛洵 《纯粹数学与应用数学》2010,26(3):420-425
证明了如果空间类K为D-空间类或闭遗传不可约空间类,则I(K)包含K.这一结果对于K为D空间类和闭遗传不可约空间类,肯定地回答了I(K)是否包含I^2(K)问题. 相似文献
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Xiaoli CHEN 《数学研究与评论》2012,32(3):337-345
In this paper,the author proves that Multiplier operator is bounded on BMO(Rn),LMO(Rn) and CBMOρ,λ(Rn)respectively if some concellation conditions are satisfied. 相似文献
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In the first part of this note, we mainly prove that monotone metacompactness is hereditary with respect to closed subspaces and open Fó-subspaces. For a generalized ordered (GO)-space X, we also show that X is monotonically metacompact if and only if its closed linearly ordered extension X* is monotonically metacompact. We also point out that every non-Archimedean space X is monotonically ultraparacompact. In the second part of this note, we give an alternate proof of the result that McAuley space is paracompact and metacompact. 相似文献
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基于(λ,μ)-反模糊子群概念及其基本性质,深入刻画了(λ,μ)-反模糊子群以及(λ,μ)-反模糊正规子群的结构.首先讨论了群G的(λ,μ)-反模糊子群在G的不同元素上隶属度的分布情况,其次研究了(λ,μ)-反模糊正规子群在G的不同元素上隶属度的分布情况,最后对循环群和阿贝尔群上(λ,μ)-反模糊子群及正规子群的结构进行详细讨论并给出了相应的结果. 相似文献