Re: Is a function a relation?
Date: Wed, 24 Jun 2009 21:26:04 -0700 (PDT)
On Jun 25, 3:15 am, "Brian Selzer" <br..._at_selzer-software.com> wrote:
> "David BL" <davi..._at_iinet.net.au> wrote in message
> > I prefer to consider the RM as a pure mathematical formalism divorced
> > from "interpretations" (i.e. external predicates and so forth).
> I can't see how that is even possible, since the extension of a predicate,
> regardless of whether it is internal or external, is a collection of atomic
> formulae, each of which must be judged to be true or false under an
> interpretation. Under the Closed World Interpretation, only those atomic
> formulae that are judged to be true are represented, but the judgement must
> still be made, and that requires the assignment of meaning to each term in
> each atomic formula. I am not saying that the assignment of meaning and the
> judgement of truth which are the constituents of interpretation should not
> be isolated, but I think it is a gross oversimplification to deny that they
> play a part altogether in relational database theory.
What I mean is that one shouldn't confuse pure mathematical systems such as set theory with how they are applied in the real world.
A mathematical relation as just a set of tuples.
I agree that the topic of interpretation is relevant to database theory. Received on Thu Jun 25 2009 - 06:26:04 CEST