Re: Objects and Relations

On Feb 9, 9:25 am, "JOG" <j..._at_cs.nott.ac.uk> wrote:
> On Feb 9, 11:58 am, "David BL" <davi..._at_iinet.net.au> wrote:
>
>
>
> > On Feb 9, 12:09 pm, Gene Wirchenko <g..._at_ocis.net> wrote:
>
> > > "David BL" <davi..._at_iinet.net.au> wrote:
>
> > > [snip]
>
> > > >All the above comes down to definition. Your usage of "model" is
> > > >different to mine. I restrict it to the narrow sense of the
> > > >representation of knowledge (in the form of attributes and
> > > >relationships) about external entities. I define "simulation" to be
>
> > > By that, a clay model of an automobile would not be a model. I
> > > think you have an overly-restrictive definition.
>
> > The subject of this thread is a comparison of OO and RM. Does it
> > matter if it doesn't encompass clay models? How is it too restrictive
> > for database systems, RM or cdt?
>
> > > >about creating a working machine that happens to *mimic* reality with
> > > >no intention of storing knowledge about external entities. Are you
> > > >saying such a distinction doesn't exist? If so then we disagree. If
> > > >it is merely over what the words "model" and "simulation" mean there
> > > >is nothing interesting to discuss.
>
> > > A simulation is a model.
>
> > > A model is a restricted representation of something. The
> > > simplifications depend on what the model is to be used for. If a
> > > model for aerodynamic testing, the shape of a car would be modelled.
> > > The sound system probably would not be in the model (though the aerial
> > > might be).
>
> > Yes according to your definition a simulation is a model.
>
> Few things. First when you are trying to express something to people
> in a certain newsgroup it is always beneficial to use the terminology
> specific to that domain if one wants to be listened to. Out of his own
> goodwill, mAsterdam maintains an extremely good glossary for the
> newsgroup, and that really should be the first port of call.
>
> Second, it is worth noting that it has been written that Codd
> regretted naming his theories the relational "Model", very much
> because of this sort of confusion. RM is about recording and
> manipulating propositions, and not really about "modelling" at all.

And yet we employ techniques he laid out (for example the-form- formerly-known-as-1NF) when we are modeling data to be stored. So, the relational model really is also about modeling propositions/ predicates, right? --dawn

>
> Third, I am still not clear at all what the aim of this thread is. It
> all seems a bit like a lot of handwaving in search of an actual point.
> A point that I am yet to hear succinctly put.
Received on Fri Feb 09 2007 - 23:58:15 CET