Re: Guessing?

On May 28, 10:28 am, paul c <toledoby..._at_ac.ooyah> wrote:
> David BL wrote:
> > On May 27, 9:57 pm, paul c <toledoby..._at_ac.ooyah> wrote:
> >> David BL wrote:
>
> >>> It seems to me that every base relvar will in practice have some
> >>> defined intensional definition outside the RM formalism and
> >>> inaccessible to the DBMS.
> >> A practitioner who (knowingly) tolerates or suggests that is likely
> >> either a sucker or a charlatan. (Bob B called Codd's example a straw-man.)
>
> > Consider the intensional definition :
>
> > S = set of surnames of UK prime-ministers after Thatcher
>
> > with (current) extension
>
> > S = { Major, Blair, Brown }
>
> > Only the intensional definition (which is outside the RM formalism) is
> > able to tell us how to apply updates over time.
>
> > Are you suggesting intensional definitions never exist or sometimes
> > don't exist or what?
> > ...
>
> A DBMS implementation is not concerned with questions of existence.
> Hmmm, Principle of Non-Existence?

I'm only suggesting that a DBMS implementation should respect the possibility that intensional definitions are present. Received on Wed May 28 2008 - 05:05:40 CEST