Re: An alternative to possreps

From: Bob Badour <bob_at_badour.net>
Date: Wed, 08 Jun 2011 00:17:02 -0700
Message-ID: <INmdnQCTnI50vHLQnZ2dnUVZ5radnZ2d_at_giganews.com>


David BL wrote:

> On Jun 7, 9:49 pm, Bob Badour <b..._at_badour.net> wrote:
> 

>>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?
> 
> I'm suggesting the operators define the equivalent of possreps.
> Possreps are redundant.

How do operators express that center is held invariant when changing only radius? And vice versa?

Or perhaps more clearly with complex number types: How do operators express that phase is held constant when changing only magnitude? And vice verse. Even though both realPart and imaginaryPart change? Received on Wed Jun 08 2011 - 09:17:02 CEST

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