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Topic: A few minutes of sanity
Replies: 6   Last Post: Nov 4, 2013 9:24 PM

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fom

Posts: 1,969
Registered: 12/4/12
Re: A few minutes of sanity
Posted: Nov 4, 2013 9:24 PM
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On 11/4/2013 10:48 AM, Michael F. Stemper wrote:
> On 11/04/2013 10:11 AM, fom wrote:
>> On 11/4/2013 7:50 AM, Shmuel (Seymour J.) Metz wrote:
>>> In <l4au0f$125r$1@macpro.inf.ed.ac.uk>, on 10/24/2013
>>> at 10:49 AM, richard@cogsci.ed.ac.uk (Richard Tobin) said:

>>>> In article
>>>> <0.50d8b4d000a73620c6cc.20131022013536BST.871u3ei1lz.fsf@bsb.me.uk>,
>>>> Ben Bacarisse <ben.usenet@bsb.me.uk> wrote:

>
>>>>>> - what's yellow and neither true nor false?
>>>>>> - what's non-orientable and lives in the sea?

>>>
>>>>> I hope you will follow up after a suitable head-scratching period (I'm
>>>>> stumped).

>>>
>>>> They are indeed Xorn's Lemon and Moebius Dick.
>>>
>>> WTF? Zorn's Lemma is certainly true in ZFC; shouldn't the answer be
>>> something that is formally undecidable?
>>>

>>
>> Yes. One would think so. For Zorn's lemma
>> the question should be something more like
>>
>> what is sometimes everywhere yellow and sometimes not?

>
> I'd always heard it as "What's yellow and equivalent to the
> Axiom of Choice?"
>


But shouldn't the idea to obsure it somewhat?

I had been thinking of ZF versus ZFC. In the latter,
choice holds everywhere. In the former, not.






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