Re: Proposal: 6NF

vc wrote:
> Jan Hidders wrote:
> > Is it really that hard to understand that I was talking
> > about two different ways of looking at the same thing?
>
> Yes, it is hard. I'd rather prefer one be precise when
> one talks about that sort of things. I am actually puzzled
> when one sez, be it Cardelli or anyone else, subtyping is
> subsetting and then adds something like "Oh, by the way I
> am really talking about algebraic structures, not just
> arbitrary sets". It looks like a sloppy way of describing
> things at best, or false advertizing at worst.

Also, don't algebraic structure definitions simply state the /existence/ of base sets without attempting to construct or otherwise define them apart from the specified signatures and constraints? Therefore, unless you define a multi-sorted algebra or specify an injection, it does seems pretty sloppy to talk about sub-setting.

However, I don't think Jan was doing that. I /think/ he was simply trying to point out the differing notions of subtype.

> And I do not even want to get into the oddity of the idea
> that integers can be derived from reals, by sub-typing or
> otherwise, essentially making reals somehow more
> fundamental (where do you get them from ?).

Another example is the circle-ellipse debate.

> In math, the construction goes just in the opposite
> direction, as I am sure you know.

Sure. But what has construction to do with sub-typing?

Keith -- Fraud 6 Received on Sat Oct 14 2006 - 18:59:12 CEST