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Math Forum » Discussions » sci.math.* » sci.math.independent

Topic: Countably Infinite Sets
Replies: 11   Last Post: Dec 28, 2012 9:08 PM

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William Elliot

Posts: 606
Registered: 1/8/12
Re: Countably Infinite Sets
Posted: Dec 27, 2012 9:56 PM
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On Thu, 27 Dec 2012, netzweltler wrote:

> Does the set {{1}, {1,2}, {1,2,3}, ...} contain all natural numbers?

No, it contains subsets of N, the set of positive integers.

On the other hand, the great union of your set is N.

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