Re: Codd provided appropriate mathematics ... (was Re: Relational and MV (response to "foundations of relational theory"))

"Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message news:c18u0i$skr$1_at_news.netins.net...
> "mountain man" <hobbit_at_southern_seaweed.com.op> wrote in message
> news:dQRZb.70077$Wa.44456_at_news-server.bigpond.net.au...
> > "Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message
> > news:c12ia2$p0l$1_at_news.netins.net...
> > > "mountain man" <hobbit_at_southern_seaweed.com.op> wrote in message
> > > news:r3%Yb.66336$Wa.13812_at_news-server.bigpond.net.au...
> > > > "Neo" <neo55592_at_hotmail.com> wrote in message
> > > > news:4b45d3ad.0402181740.42d42bc2_at_posting.google.com...
> > > > > Execute("SELECT * FROM BOB WHERE OUTPUT = FALSE");
> > > > >
> > > > > 19 Records Found:
> > > > > "Codd provided appropriate mathematical backing to all of his
> claims"
> > > >
> > > > ...[trim]...
> > > >
> > > > I'd be interested to hear about this. Empirical
> > > > evidence should either exist or not exist. The
> > > > "all" word might be troublesome.
> > >
> > > I have found at least one area where Codd takes a jump mathematically.
> > I'm
> > > not taking the time right now to get his exact wording, but a summary
is
> > > this:
> > >
> > > 1. In his 1970 paper, Codd goes through the mathematics of relations
> and
> > > indicates that elements in relations could, themselves, be relations.
> > > However, he suggests starting simply with relations that do not
contain
> > > relations.
> > > 2. In the 1974 paper and in the normal form discussions, normal forms
> are
> > > described so that "n" normal form is data that is in 1st normal form
and
> > > then ...
> > > 3. There is no mathematical foundation for putting the data into 1NF
> > except
> > > for what Codd and his followers indicate is that the model should be
as
> > > simple as possible but not simpler and they indicate that without
> > resorting
> > > to nested relations, the model is as simple as is needed. This is NOT
a
> > > mathematical conclusion.
> >
> >
> > It seems to be more of an hypothesis.
>
> Yes, but even as a hypothesis, it would not be a mathematical one. That
is
> fine with me as I have many hypotheses that would require emperical data
to
> be proven. However, it seems to me that a lot of students of relational
> database theory mistakenly think that there is some mathematical proof
that
> shows us this is the way to go in how we store and query data.

My first read through Date's 7th edition (database systems) left me with the impression that the author has essentially formalised a set theory approach to the manipulation of data in a database.

> While there
> is a mathematical model involved, it is just one of many ways to model
data
> and there is no mathematical proof that it is "right" and that any other
is
> wrong. There is also, to my knowledge, no emperical data to suggest that
it
> is "right" from the perspective of yielding overall better, faster, more
> reliable, etc software applications.

I doubt whether one could in fact benchmark the relational *model*, but rather only an implementation instance of the model. Thus I'd not expect there to ever be any empiricism in this area.

>So, I think there is a significant
> myth about relational theory that is written in many college database
texts.

Is this not a *part* of the nature of academia? Commentaries on commentaries?

Pete Brown
Falls Creek
NSW
Oz. Received on Mon Feb 23 2004 - 06:02:25 CET