Re: Database design

Mark Johnson wrote:
> "Marshall Spight" <marshall.spight_at_gmail.com> wrote:
>
> >> And at what point would a relation of paragraphs, say, which would
> >> include a sort attribute, have to be fairly termed an ordered
> >> relation?
>
> >Never.
>
> Even if the set were so ordered?

Once you order a set, it's not a set any more.

Let's say you have some integers: 1 and 2. Analogous to the set S and the ordering relation R. Now, apply an operation, division, (analogous to the operation sort) to the two operands. The result is 1/2. Is it an integer? No? Why not?

Again, S is unordered. The pair (S, R) is ordered. The fact that R exists does not change the nature of S.

> >> Or is such simply defined out of the realm of possibility,
>
> >Yes.
>
> But doesn't that just strike you as mere wordplay?

I say "the formal definition of a mathematical term"; you say "mere wordplay."

> If a set is
> ordered, and one declares it is not, when is it that one can tell the
> emperor he should put some clothes on?

If a data structure is ordered, and one calls it a set, one has revealed one's lack of understanding of the term.

> If a building is on fire, I for one would not stand there and say -
> fire, what fire? Building, what building?

After the building burned to the ground, and all that was left was a dumpster full of ashes, would you still call it a building? To do otherwise is mere wordplay.

Marshall Received on Wed Feb 22 2006 - 20:19:07 CET