Re: On Formal IS-A definition

From: Reinier Post <rp_at_raampje.lan>
Date: 06 May 2010 23:14:33 GMT
Message-ID: <4be34d59$0$14133$>

Nilone wrote:

>On May 3, 11:49 pm, r..._at_raampje.lan (Reinier Post) wrote:
>> Tegiri Nenashi wrote:
>> >Perhaps you are not comfortable with the idea than more than one tuple
>> >of Carnivores2 might represent each "entity"?
>> That's what I wrote, didn't I?  It's strange.  It's very unusual.
>> It doesn't fit in with ER modelling, for instance.
>Perhaps we should name the relvar CarnivoreEatsAnimal? It would
>correspond to the Eats relationship between Carnivore and Animal
>entities in the ER model.

Exactly: it's a relationship, not an entity, while IS-A is supposed to relate two entities.

Received on Thu May 06 2010 - 18:14:33 CDT

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