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Re: Normalisation

From: Jan Hidders <jan.hidders_at_REMOVETHIS.pandora.be>
Date: Wed, 13 Jul 2005 22:00:04 GMT
Message-ID: <E9gBe.144135$ee2.7610436@phobos.telenet-ops.be>


VC wrote:

> "Jan Hidders" <jan.hidders_at_REMOVETHIS.pandora.be> wrote in message 
> news:%reBe.144048$9f4.7479324_at_phobos.telenet-ops.be...
> 

>>VC wrote:
>>
>>>"Jan Hidders" <jan.hidders_at_REMOVETHIS.pandora.be> wrote in message
>>>news:FwWAe.143403$A03.7623726_at_phobos.telenet-ops.be...
>>>
>>>
>>>>VC wrote:
>>>>
>>>>
>>>>>"Jan Hidders" <jan.hidders_at_REMOVETHIS.pandora.be> wrote in message
>>>>>news:AyVye.138732$g63.7370802_at_phobos.telenet-ops.be...
>>>>>[...]
>>>>>
>>>>>
>>>>>
>>>>>>Ah, but now you are using the domain or relations, right? There is a
>>>>>>problem with that domain. It doesn't exist. The collection of all
>>>>>>relations is a proper class, and not a set, but domains have to be
>>>>>>sets.
>>>>>
>>>>>The collection of all relations is most certainly a set, and
>>>>>therefore, a domain, domain being a synonym of set. The term "proper
>>>>>class" implies that you talk in terms of set theory other than ZF (
>>>>>Zermelo - Fraenkel ) ). There is no need to do so for the reltional
>>>>>model unless you can show there is ;)
>>>>
>>>>There is indeed no such need, unless of course you want to define the
>>>>domain of relations, which you cannot do in ZF.
>>>
>>> The onus of proof of such impossibility is squarely on your shoulders.
>>>Please oblige (define a collection/domain of relations, within ZF, which
>>>ain't a set).
>>
>>Defining a collection of relations within ZF that is not a set, is neither
>>here nor there.
> 
> I am sorry but your response does not make any sense whatsoever.  What  is 
> "neither here nor there" supposed to mean ?

It means that it is irrelevant for the question whether you can define the domain of relations in ZF. Note that is says "the domain" and not "a domain".

Received on Wed Jul 13 2005 - 17:00:04 CDT

Original text of this message

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