On the cardinality of S(n)-Spaces

被引:2
|
作者
Osipov, Alexander V. [1 ]
机构
[1] Ural Fed Univ, Krasovskii Inst Math & Mech, Ekaterinburg, Russia
关键词
54A25; 54D10; 54D25; Cardinal function; S(n)-space; theta(n)-closure; S(n)-theta-closed; quasi-Menger number;
D O I
10.2989/16073606.2019.1672112
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
In this paper, for a topological space X and any positive integer n, we define the cardinal functions sL(theta(n)) (X), theta(n)-quasi-Menger number qM(theta(n)) (X) and s(n)-quasi-Menger number qM(s(n)) (X). We prove the following statements: For every S(2n)-space X, |X| <= 2(sL) theta (n) (X) kappa(theta (n)) (X).For every S(2n)-space X, |X| <= 2(qM) theta (n) (X) kappa(theta (n)) (X).For every S(2n)-space X, |X| <= 2(qM) s (n) (X) kappa(theta (n)) (X).Similar results are stated for S(2n - 1)-spaces.
引用
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页码:121 / 128
页数:8
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