On some cardinal functions related to quasi-uniformities

被引:0
|
作者
Künzi, HPA [1 ]
Losonczi, A [1 ]
机构
[1] Univ Bern, Dept Math, CH-3012 Bern, Switzerland
来源
HOUSTON JOURNAL OF MATHEMATICS | 2000年 / 26卷 / 02期
关键词
transitive; quasi-uniformity; unique quasi-uniformity; quasi-proximity class;
D O I
暂无
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
We show that if a topological space possesses two (distinct) compatible quasi-uniformities, then it admits at least 2(2 kappa)0 nontransitive quasi-uniformities. We also prove that if a quasi-uniform space (X, W) has a subspace A and an entourage W such that either {W(rc) :x is an element of A} or {W-1(x) :x is an element of A} does not have a subcollection of cardinality smaller than kappa covering A, then there are at least 2(2 kappa) quasi-uniformities belonging to the quasi-proximity class of W. (Here re is an infinite cardinal.) Finally we show that if the quasi-proximity class pi(W) of a quasi-uniformity W contains more than one quasi-uniformity and its coarsest member is transitive, then there are at least 2(2 kappa)0 transitive quasi-uniformities belonging to the quasi-proximity class pi(W).
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页码:299 / 313
页数:15
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