Re: Zorn's lemma for families of subsets of a countable set

From: David C. Ullrich (ullrich_at_math.okstate.edu)
Date: 06/23/04


Date: Wed, 23 Jun 2004 06:19:39 -0500

On 23 Jun 2004 00:10:48 -0700, kramsay@aol.com (Keith Ramsay) wrote:

>Is the special case of Zorn's lemma where the ordered
>set consists of a family of subsets of a countable set,
>ordered by inclusion, a theorem of ZF?

A wild-assed guess would be "surely not".

Proof: How could it be? QED.

Proof: It's true for families of _finite_ subsets of N,
but not all sets are finite. QED.

There may be a few details missing in those proofs...

>Keith Ramsay

************************

David C. Ullrich



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