Re: more on delete from join

From: paul c <toledobythesea_at_oohay.ac>
Date: Thu, 27 Aug 2009 02:35:54 GMT
Message-ID: <eimlm.40861$Db2.21494_at_edtnps83>


Mr. Scott wrote:
> "paul c" <toledobythesea_at_oohay.ac> wrote in message
> news:RYhlm.40820$Db2.17042_at_edtnps83...

>> Mr. Scott wrote:
>>> "paul c" <toledobythesea_at_oohay.ac> wrote in message
>> ...
>>>> Insert to a base relvar represents a conclusion: R =: R UNION A conludes 
>>>> R AND A.
>>> It concludes R OR A.  R AND A would be just A, provided A is in R.
>> I think you mean R <AND> A would be just A, provided A is in R and they 
>> have the same heading.  Whether or not A is in R, after the assignment, 
>> all propositions that A stands for and all propositions that R previously 
>> stood for are true, eg., if r1,r2,...,rn and a1,a2,...,an are the original 
>> propositions, r1 AND r2 AND ... a1 AND a2 is true as far as R is 
>> concerned. .

>
> I mean R OR A. Under the closed world interpretation, the disjunction of
> the collection of facts represented by a table is interpreted as the
> conjunction of those facts along with the negation of the facts represented
> by the complement of the table, the assumption being that what is stated is
> supposed to be true and what isn't isn't. I mean R OR A because the
> disjunctions of the collections of facts represented in R and in A are
> combined into the disjunction of a single collection of facts prior to
> applying the closed world interpretation.
>
>

I don't know if the plural 'disjunctions' is a typo'. Do you mean that the resulting value of R stands for "r1 OR r2, etc." is true? Received on Thu Aug 27 2009 - 04:35:54 CEST

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