Descendingly incomplete ultrafilters
Descendingly incomplete ultrafilters
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递减不完全超滤器
DOI：
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发表时间：
1967
期刊：
影响因子：
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通讯作者：
C. C. Chang
中科院分区：
文献类型：
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作者：
C. C. Chang
介绍。众所周知，只要集合 I 的基数不是很大，集合 I 上的每个非主超滤器 D 都是 c 不完全的。 （我们建议读者参阅 Keisler 和 Tarski [5] 的综合论文，以获取所有相关信息和进一步的参考资料。）由于超滤器在其成员的有限交集下是封闭的，因此很容易看出 D 是共不完备的，相当于说存在一个共名序列
Introduction. It is well known that every nonprincipal ultrafilter D on a set I is c-incomplete, provided the cardinal of the set I is not exceedingly large. (We refer the reader to the comprehensive paper by Keisler and Tarski [5] for all relevant information and further references.) Since ultrafilters are closed under finite intersections of its members, it is easy to see that D being co-incomplete is equivalent to saying that there exists a co-termed sequence