a proper subset of a infinite set can be a infinite set itsefl.

送交者: steven 于 2006-12-19, 16:12:10:

回答: 无穷多的点 is a countable set 由 HunHunSheng 于 2006-12-19, 16:06:32:

S = I - {1} is a proper subset I where I is the set of all natural number, and I - {1} is infinite, since S is a proper subset, it is definitely a segment of the number line.

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It is about countable vs uncountable not finite vs infinite - HunHunSheng (224 bytes) 2006-12-19, 16:23:08 (116411)
- what do you mean uncountable? You can't count integer? - steven (105 bytes) 2006-12-19, 16:48:55 (116417)

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