Re: Peter Chen and Charles Bachman

From: D Guntermann <guntermann_at_hotmail.com>
Date: Wed, 5 May 2004 17:52:33 GMT
Message-ID: <Hx95nL.F8J_at_news.boeing.com>


"Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message news:c7ando$tol$1_at_news.netins.net...
> "Leandro Guimarães Faria Corsetti Dutra" <leandro_at_dutra.fastmail.fm> wrote
> in message news:pan.2004.05.05.02.38.23.931293_at_dutra.fastmail.fm...
> > Em Tue, 04 May 2004 17:16:28 -0500, Dawn M. Wolthuis escreveu:
> >
> > >> Diagrams aren't models...
> > >
> > > I'll accept that diagrams, in themselves, are not full mathematical
> > > theories, but models they often are, it seems to me. What is your
> > > definition of "model" (as a noun)?
> >
> > A model must include all aspects of the database, or it will
> > be only a draft.

Wouldn't a model that includes all aspects of the database be an implementation? Perhaps the word "all" is a little strong.

>

> With the number of dialogs we have that include information relevant to
> databases, but "orthogonal" to relational theory, my conclusion is that by
> your definition relational theory is not a model -- is that correct?

I don't want to put words in his mouth, but I think he is arguing just the opposite.

I'm sure many in this group have already seen the article, but the following by Chris Date gives rise to what I agree are some of the issues and distinctions that are relevent to what we call and how we use models. See "Models, models, everywhere, nor any time to think." (http://www.pgro.uk7.net/cjd3a.htm).

  • Dan
>

> >
> > A diagram can hardly be expected to represent, say, all
> > constraints in a database.
> >
> > Not to mention their maintenance tends to become
> > counterproductive as the database grows in complexity and size.
> >
> > They are nice as drafts in the early stages of modelling and
> > for presentation.
> >
> >
> > --
> > Leandro Guimarães Faria Corsetti Dutra +55 (11) 5685 2219
> > Av Sgto Geraldo Santana, 1100 6/71 +55 (11) 5686 9607
> > 04.674-000 São Paulo, SP BRASIL
> > http://br.geocities.com./lgcdutra/
>
> Received on Wed May 05 2004 - 19:52:33 CEST

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