Re: An alternative to possreps
Date: Wed, 8 Jun 2011 03:08:00 -0700 (PDT)
Message-ID: <dfde7cfc-d8d1-446b-99e7-0941c7e1608b_at_n11g2000yqf.googlegroups.com>
On 8 jun, 03:55, David BL <davi..._at_iinet.net.au> wrote:
> On Jun 7, 9:49 pm, Bob Badour <b..._at_badour.net> wrote:
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> > David BL wrote:
> > > On Jun 6, 9:26 pm, Erwin <e.sm..._at_myonline.be> wrote:
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> > >>On 31 mei, 11:54, David BL <davi..._at_iinet.net.au> wrote:
>
> > >>>Is there anything in TTM that prohibits one from making every type a
> > >>>dummy type? Would that make it essentially the same approach which
> > >>>I've described?
>
> > >>Not "in TTM". What prohibits this is "reality", I'd rather say.
>
> > >>If you're interested in a subset of T, then you can't define this
> > >>subset by means of UNIONs involving T.
>
> > > Yes, but that is not a problem. Let Ellipse be a "dummy type". If
> > > you're interested in a subtype Circle of Ellipse then you can simply
> > > declare Circle as another dummy type. I'm assuming you can declare
> > > subtype relationships between dummy types. In my approach you use
> > > these declarations:
>
> > > type Ellipse;
> > > type Circle;
> > > Circle isa Ellipse;
>
> > > I consider types like Circle and Ellipse to be defined by their
> > > operators. In that sense there is no problem treating all types as
> > > "dummy types".
>
> > Either the operators define the equivalent of possreps or the type model
> > doesn't really describe ellipses and circles. So what are you trying
> > to achieve?
>
> I'm suggesting the operators define the equivalent of possreps.
> Possreps are redundant.
>
> The equality operator has a role to play in this. The possrep
> constraint which specifies which representations of ellipses are
> circles is instead defined indirectly by the equality operator (which
> defines which representations of ellipses are equal to some
> representation of a circle).- Tekst uit oorspronkelijk bericht niet weergeven -
>
> - Tekst uit oorspronkelijk bericht weergeven -
Plus, circles-and-ellipses are only in the realms of the inheritance model. Possreps also have a role to play without inheritance. Received on Wed Jun 08 2011 - 12:08:00 CEST