Re: On the usefulness of tables definitions in RM...

On 20 août, 18:16, Roy Hann <specia..._at_processed.almost.meat> wrote:
> Cimode wrote:
> > I lately came to the conclusion that teaching relation structures and
> > manipulations by using tables inherently induces a bias to think of
> > relations as relation values as opposed to relation variables.
> > However, I believe that tables are elements of the presentation layer
> > since they are only *one* possible representation in time of a
> > specific relation.
>
> > I am curious on whether this confuses more than it helps as far as
> > operation definitions are concerned.  What representations are to be
> > preferred to avoid confusions ?  In what context ?
>
> > Opinions welcome.
>
> When I am teaching I start by writing out a few propositions in full,
> but mixing up the order, and I draw attention to the fact that I am
> doing it.
>
> I then invite the class to tell me if I have repeated myself anywhere
> (which I usually haven't).
>
> I then tell them that to simplify my presentation and to make it easier
> to answer questions like that "at a glance" *BUT FOR NO OTHER REASON*, I
> will discipline myself to always write the propositions in a single
> consistent form.
>
> I then point out that a single predicate can be written which is of a
> form that all the propositions fit, so I can leave out all the
> extraneous verbiage and just *list* the values to plug into the
> predicate.
>
> I then re-write all my propositions just as lists of values, neatly
> lined up, so that it appears tabular.
>
> I then remind the class that the tabular appearance is merely a happy
> accident.
Thanks for this insight. I am curious as to what do you think is gained by your students, in the perspective of understanding relations, in going through such efforts.

> Roy
Received on Fri Aug 20 2010 - 21:41:35 CEST