Re: Codd's Information Principle
From: paul c <toledobythesea_at_oohay.ac>
Date: Mon, 02 Nov 2009 01:03:38 GMT
Message-ID: <KdqHm.51163$PH1.49256_at_edtnps82>
>> Bob Badour wrote:
>>
>>> paul c wrote:
>>
>> ...
>>
>>>> Didn't mean to suggest otherwise. Sometimes the immediate expert
>>>> objection to the 'primrose path' turns out to be an advantage if the
>>>> idea is allowed to breath.
>>>>
>>>> But one point seems very immediate to me - for any given relational
>>>> expression, there is only one equivalent extension.
>>>
>>> I don't follow that at all.
>>
>> If you mean the last sentence, I could expand it by saying that for
>> any given purpose, in other words any given application, I think that
>> single extension must have one interpretation. Since the expression
>> might not involve any algebraic operations, I think it is best to
>> discard those in the interpretation, no matter how the extension was
>> formed. I say 'best' because that seems sufficient to me and I don't
>> see how including those ops is necessary. I would like to know what
>> problems this causes, eg., I don't see that
>> inconsistences/contradictions or loss of utility or inability to
>> optimize result from it.
>
> I cannot make sense of what you wrote.
Date: Mon, 02 Nov 2009 01:03:38 GMT
Message-ID: <KdqHm.51163$PH1.49256_at_edtnps82>
Bob Badour wrote:
> paul c wrote: >
>> Bob Badour wrote:
>>
>>> paul c wrote:
>>
>> ...
>>
>>>> Didn't mean to suggest otherwise. Sometimes the immediate expert
>>>> objection to the 'primrose path' turns out to be an advantage if the
>>>> idea is allowed to breath.
>>>>
>>>> But one point seems very immediate to me - for any given relational
>>>> expression, there is only one equivalent extension.
>>>
>>> I don't follow that at all.
>>
>> If you mean the last sentence, I could expand it by saying that for
>> any given purpose, in other words any given application, I think that
>> single extension must have one interpretation. Since the expression
>> might not involve any algebraic operations, I think it is best to
>> discard those in the interpretation, no matter how the extension was
>> formed. I say 'best' because that seems sufficient to me and I don't
>> see how including those ops is necessary. I would like to know what
>> problems this causes, eg., I don't see that
>> inconsistences/contradictions or loss of utility or inability to
>> optimize result from it.
>
> I cannot make sense of what you wrote.
Best I can do at the moment without a clue or two. If Bob B doesn't get any part of it either there is little point embellishing or possibly I have lapsed into mysticism, will reserve judgment for now. Oh well, that's life. Received on Mon Nov 02 2009 - 02:03:38 CET