We present several results on compact Hausdorff spaces which can be represented as unions of nice subspaces. Some typical results are: If X is a compact Hausdorff space, and X = U(alpha < kappa)X(alpha), where each X(alpha) is kappa-refinable and PSI(X(alpha)) less-than-or-equal-to kappa, then (i) every nonempty G(kappa)-subset of X contains a point of character less-than-or-equal-to kappa, (ii) if x is-an-element-of X, chi(x, X) = mu > kappa and mu is regular, then there exists a discrete sequence {x(alpha): alpha < mu} in X such that x(alpha) --> x, (iii) if A is a nonclosed subset of X, then there exists a point x is-an-element-of X\A and a filter base F of subsets of A such that \F\ less-than-or-equal-to kappa and F --> x. We also show that if a compact Hausdorff space X is a union of countably many metrizable spaces, X has no isolated points and c(X) = omega0, then X is a compactification of the space of irrationals.
机构:
Ben Gurion Univ Negev, Dept Math, PO 653, Beer Sheva, IsraelBen Gurion Univ Negev, Dept Math, PO 653, Beer Sheva, Israel
Gabriyelyan, Saak S.
Morris, Sidney A.
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Federat Univ Australia, Fac Sci & Technol, POB 663, Ballarat, Vic 3353, Australia
La Trobe Univ, Dept Math & Stat, Melbourne, Vic 3086, AustraliaBen Gurion Univ Negev, Dept Math, PO 653, Beer Sheva, Israel
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Univ Autonoma Metropolitana, Dept Matemat, Av San Rafael Atlixco 186, Mexico City 09340, DF, MexicoUniv Autonoma Metropolitana, Dept Matemat, Av San Rafael Atlixco 186, Mexico City 09340, DF, Mexico
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Univ Autonoma Metropolitana, Dept Matemat, Av San Rafael Atlixco 186, Mexico City 09340, DF, MexicoUniv Autonoma Metropolitana, Dept Matemat, Av San Rafael Atlixco 186, Mexico City 09340, DF, Mexico