Re: Normalisation

From: VC <boston103_at_hotmail.com>
Date: Tue, 12 Jul 2005 19:44:47 -0400
Message-ID: <gY2dnSJOfth2yEnfRVn-tg@comcast.com>

"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).

Thanks.

>
> -- Jan Hidders Received on Tue Jul 12 2005 - 18:44:47 CDT