Re: Proposal: 6NF

Keith H Duggar schreef:

> 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.

Just to confirm, yes, I was.

• Jan Hidders