Re: In an RDBMS, what does "Data" mean?

"Paul" <paul_at_test.com> wrote in message news:kJ_qc.6454$NK4.656018_at_stones.force9.net...
> Anthony W. Youngman wrote:
> > If we can't set up an experiment (even a Gedanken thought experiment),
> > then relational theory is not provable, therefor it is not scientific,
> > therefor it is irrelevant to the real world, therefor why the hell are
> > we using it :-)
>
> Newtonian mechanics is more like a particular instance of a database in
> the relational model, rather than the model itself.
>
> The relational model is really just an implementation of first-order
> predicate logic that is suitable for computers.
>
> Logic is more like a "meta-theory": it's kind of how we reason *about
> how we reason*, so it's a bit self-referential.
>
> For a particular database we can test it experimentally: we add data,
> query it and check that the answers correspond with reality.
>
> For first-order predicate logic itself, it's almost axiomatic that it
> corresponds to reality, because we are saying this is how we argue
> logically by definition. Godel proved that first order logic is
> "complete" in some sense (see here for example:
> http://www.sm.luth.se/~torkel/eget/godel/completeness.html), though the
> whole area of Godel is guaranteed to cause confusion and
> misunderstanding, and will possibly explode your brain.
>
> >> (Incidentally, can we agree that while consistency is not sufficient to
> >> prove the correctness of a data model, it is necessary?)
> >>
> > Of course. I'd actually rephrase that. While (internal) consistency may
> > prove the model to be correct (mathematically), we need external
> > consistency to prove the model accurate (here we go - arguing over the
> > meaning of words again :-)
>
> But in order to prove the model is accurate externally we'd have to use
> logic. So we've got a chicken and egg situation here. What logic is
> external to logic itself?

Random truths (Chaitin) and unprovable truths (Godel). See http://www.mountainman.com.au/GIF/logic_space_1.jpg

Pete Brown
Falls Creek
Oz Received on Thu May 20 2004 - 12:32:44 CEST