Re: Fraud Number 3: U-Gene

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Tue, 20 Jun 2006 20:58:47 GMT
Message-ID: <bkZlg.108$pu3.1821@ursa-nb00s0.nbnet.nb.ca>

Tony D wrote:

> Cimode wrote:
>

>>First, I am aware of Date's definition and I do not quite feel
>>confortable with it because it focuses too much on structural
>>definition and not enough on the characteristics values extraction from
>>domains.  Neverthless, Date's is logically correct: it's a matter of
>>perspective.

>
> Well that's reassuring; although you're right on the potential for
> overemphasising structure.
>

>>I also believe some of Date's definition can also lead to
>>confusion..For instance, Date's definition relvar could lead to
>>confusion with the definition of an attribute.  (both have a name, a
>>data type and may hold a value in time).  If we define, attribute and
>>relvar alike, one take the risk of confusing them...

>
> But I'm not sure how you could confuse an attribute with a relvar. A
> relvar is a variable and can indicate different values at different
> times. A relation value is value; like an integer value, it never
> changes.

Ah, but an attribute is a variable a la predicate calculus. See 'bound variable' and 'free variable' for what I mean. Received on Tue Jun 20 2006 - 15:58:47 CDT