Re: An alternative to possreps

From: Bob Badour <bob_at_badour.net>
Date: Tue, 07 Jun 2011 06:49:50 -0700
Message-ID: <mZWdnYRez-nlsXPQnZ2dnUVZ5ridnZ2d_at_giganews.com>


David BL wrote:

> On Jun 6, 9:26 pm, Erwin <e.sm..._at_myonline.be> wrote:
>

>>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? Received on Tue Jun 07 2011 - 15:49:50 CEST

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