作者recorriendo (孟新)
看板Math
标题[其他] Well-ordering的问题
时间Mon Feb 7 08:39:51 2011
Let D be the set of decreasing functions f: N -> N. (N 是自然数集)
The relation < on D is defined as follows: f < g iff there is an natural
number n such that f(n) < g(n) and f(i)=g(i) for all i < n.
Let S be a nonempty subset of D. Show that S has a least element under <.
想了一些方法可是好像都不太对
不知道有没有熟悉集合论的高手帮忙解此题
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