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Re: Normalisation

From: Jan Hidders <jan.hidders_at_REMOVETHIS.pandora.be>
Date: Wed, 13 Jul 2005 20:03:07 GMT
Message-ID: <%reBe.144048$9f4.7479324@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.

Received on Wed Jul 13 2005 - 15:03:07 CDT

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