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1.
证明了对任何连通的T1拓扑空间(X,T)和X上的一个理想I,由{U\I:U∈T,J∈I}生成的理想拓扑T也是连通的,当且仅当I中每个元素的内部为空.  相似文献   

2.
本文证明了几个弱基度量化定理,主要结果如下:(1)拓扑空间X是可度量化当且仅当X有弱基B满足如果对每个收敛序列{xn}→x及x的每个开邻域U,存在m∈N,使得T(x,m)∪→∪(x,m)且仅在B的限多个元素与T(x,m)及X-U相交,其中T(x,m)={xn:n≥m}∪{x};(2)拓扑空间X是可度量化当且仅当X有一个弱展开G1,G2…,使得对每个自然数i及任意U1,U2∈Gi+1且U1∩∪2≠Φ  相似文献   

3.
本文给出了正则和正规空间的4个判定定理:定理1 拓扑空间 X 为正则空间,当且仅当对于 X 中的任一点x 以及 x 中不含 x 的任一闭集 B,x、B 分别有闭邻域 U、V,使得U∩V=.定理2 拓扑空间 X 为正规空间,当且仅当对于 X 中的任意不相交的闭集 A、B、A、B分别有不相交的闭邻域 U、V,使U∩V=.定理3 拓扑空间 X 为正则空间,当且仅当对 X 中的任一点 x 以及不含点 x 的任意闭集B,分别有 x,B 的闭邻域 U、V,使得 i(U)∩i(V)=.定理4 拓扑空间 X 为正规空间,当且仅当对 X 中的任意两个不相交的闭集 A、B,A、B 分别有闭邻域 U、V,使得 i(U)∩i(V)=.  相似文献   

4.
<正> 日本著名拓扑学家J.Nagata证明如下定理:定理1 空间X是可度量化的当且仅当X有g-函数满足:(1)对任意x∈X及任意U∈N_x,n∈N,使x[∪{g(n,y)|y∈X-U;(2)对任意YX,∪{g~2(n,y)|∈Y},其中g~2(n,y)=∪(g(n,z)|z∈g(n,y)}。在此定理之后,J.Nagata提出:能否找山一个弱于该定理(2)的条件而与条件(1)一起刻划X的可度量性呢?下面定理给出肯定回答。定理2 空间X是可度量化的当且仅当X有g-函数满足定理1的(1)和下面的(2′)。即(2′)对任意YX,。  相似文献   

5.
本又给出了由分明拓扑空间(X,T)置成的LF拓扑空间(LX,X(T)),研究了它的拓扑基结构,证明了(LX,X(T))是T2的,连通的空间,当且仅当(X,T)是T2的,连通的空间。  相似文献   

6.
探讨了关于δθ可加空间遗传性的一个问题,获得了δθ可加空间的两组等价刻画.主要结论有:X是遗传δθ可加空间当且仅当每一个散射分解有一个开的δθ膨胀序列;设X是拓扑空间,则下列条件等价:(1)X是遗传δθ可加的.(2)X的每个开覆盖U={Uα∶α<γ}有一个开的δθ加细序列〈Vn ={V(n,α)∶α<γ}〉n∈ω,使得(**)n∈ω,(**)α<γ,Gα(*)V(n,α)(*)Uα.(3)X的每个单调递增的开覆盖U={Uα∶α<γ}有一个开的δθ加细序列〈Vn〉n∈ω,使得(**)n∈ω,(**)x∈X;存在V∈Vn 使得x∈V(*)Uα(x).  相似文献   

7.
集值映射的拓扑遍历性、传递性与混沌   总被引:1,自引:0,他引:1  
设f∈C0(X,X),f为由f所诱导的集值映射.本文证明了:对任意m≥2, fm是拓扑遍历(强拓扑遍历)的当且仅当fm=fm是拓扑遍历(强拓扑遍历)的.设T为树,对于f∈C0(T,T),我们给出了f是混沌的22个等价条件,其中有些等价条件是区间上相应结果的推广.  相似文献   

8.
<正>文[1]中只给出了部分半分离性的等价形式,在此将半T:(i=0,1,2,3,4)公理都给以等价形式,并将文[1]中已给出的等价形式加以扩充.定义1拓扑空间X的子集A称为X中的半开集当且仅当存在X中的开集O,使得O(?)A(?)(?).X中所有半开集所组成的族记为S.O(X).定义2设X为拓扑空间,x∈X,u(?)X.如果存在一个包含x的半开集v包含于u.  相似文献   

9.
所为一个格具有Σcore紧性(ΣF-core紧性),是指在赋以scott拓扑(score开滤子拓扑)之后,这个格作为拓扑空间是core紧的。本文证明了若ΣF(L)为序相容拓扑空间,则L具有ΣF-core紧性当且仅当L为连续格。  相似文献   

10.
引入了基-可数仿紧空间的概念,给出基-可数仿紧空间的一些等价刻画,获得以下结果:(i)X是基-可数仿紧空间当且仅当存在X的一开基B,|B|=ω(X),对于X的每一可数开覆盖U={Ui}i∈N,都存在B′B,使得B′={Bi}i∈N是U的局部有限的可数开加细,且BiUi;(ii)设X是正规空间,X是基-可数仿紧空间当且仅当存在的一开基B,|B|=ω(X),使得X的每一可数开覆盖都存在由B中的元构成的局部有限的收缩.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

15.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

16.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

17.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

18.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

19.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

20.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

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