Re: On Formal IS-A definition
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Wed, 12 May 2010 01:03:22 -0300
Message-ID: <4bea2890$0$12448$9a566e8b_at_news.aliant.net>
>> On 11 mei, 19:02, paul c <toledobythe..._at_oohay.ac> wrote:
>>> need to be meaningless in the face of the closed-world-assumption.
>>
>> Not always.
>>
>> Suppliers who supply packagings of no parts at all are pretty insane.
>>
>> But relvar keys that consist of no attributes at all are not. Thus a
>> catalog tuple describing a relvar key with an empty set of attributes
>> most certainly will not "need to be meaningless in the face of the
>> CWA". Quite the contrary, in fact.
>> ...
>
> But why record it?
Date: Wed, 12 May 2010 01:03:22 -0300
Message-ID: <4bea2890$0$12448$9a566e8b_at_news.aliant.net>
paul c wrote:
> Erwin wrote: >
>> On 11 mei, 19:02, paul c <toledobythe..._at_oohay.ac> wrote:
> > ... >>>> interpretation, eg., perhaps a tuple with an empty set of parts would
>>> (I didn't have RVA's in mind, more what you might call
>>> Set-Valued-Attributes and those certainly do need some basis for
>>> need to be meaningless in the face of the closed-world-assumption.
>>
>> Not always.
>>
>> Suppliers who supply packagings of no parts at all are pretty insane.
>>
>> But relvar keys that consist of no attributes at all are not. Thus a
>> catalog tuple describing a relvar key with an empty set of attributes
>> most certainly will not "need to be meaningless in the face of the
>> CWA". Quite the contrary, in fact.
>> ...
>
> But why record it?
You are questioning the utility of stating facts as fundamental as true and false. I suggest you might need to re-read Paul's post with greater care. Received on Wed May 12 2010 - 06:03:22 CEST