Re: more on delete from join
Date: Wed, 26 Aug 2009 21:40:01 GMT
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. . Received on Wed Aug 26 2009 - 23:40:01 CEST