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Topic: How many real numbers are there?
Replies: 18   Last Post: Jul 9, 2006 3:00 PM

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Denis Feldmann

Posts: 533
Registered: 4/23/06
Re: How many real numbers are there?
Posted: Jul 8, 2006 12:57 AM
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Toni Lassila a écrit :
> On 7 Jul 2006 13:30:05 -0700, "Nathan" <> wrote:

>> Mike Deeth wrote:

>>> It's well-known that a countable union of finite sets is countable.
>> Nope! You said you were working in ZF. This requires AC.
> No it doesn't.

Even a countable union of pairs can be uncountable (Cohen). You should
check your sources.

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