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Nearly Weak (?) Refinable Spaces And Base Metacompact Spaces

Posted on:2008-02-08Degree:MasterType:Thesis
Country:ChinaCandidate:X B DengFull Text:PDF
GTID:2120360215971387Subject:Applied Mathematics
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In this thesis, the covering and mapping methods are applied to makepreliminary research of the nearly weak (?) refinable space,base-metacompact,hereditarily hyperparacompact spaces, and we obtain the following results:(1) A space X is nearly weak (?) refinable space iff X is nearly discretely weak(?) refinable expandable and for every open cover u={Uα:α∈Λ} of X, then thereis a dense set D(?)X and a V=Un∈ωVn of open refinements of U such that foreach x∈D there are n∈ωandα∈Λwith x∈Uαand st(x, Vn)(?)∪β≤α Uβ;(2) Let X=Пσ∈∑ Xσbe |∑|-paracompact, then it is weak (?) refinable spaceifПσ∈F Xσis weak (?) refinable space for every F∈[ω]<ω;(3) For countable paracompace X=Пi∈ω Xi, the followings are equivalent: Xis weak (?) refinable; (?)F∈[ω]<ω,Пi∈FXi is nearly weak (?) refinable;(?)n∈ω,Пi≤n Xi is weak (?) refinable space;(4) Let f:X→Y be perfect mapping, if Y is base-metaparacompace, thenX is base-metaparacompace;(5) A space X is base-metacompact if and only if there is base B of X, with|B|=ω(X), such that every directed open cover of X has a point-finite refinementbase B', B'(?)B. such that x∈Int(st(x, B')) for any x∈X;(6) Obtain a group of equivalent characterizations of hereditarilyhyperparacompact spaces, we obtain a Tychonoff product theorems by the one ofcharacterizations.
Keywords/Search Tags:nearly weakθ|- refinable space, base-metacompact, hereditarily hyperparacompact spaces, Tychonoff product
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