Re: Smart Database Tricks
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Fri, 22 Jun 2007 10:35:03 -0300
Message-ID: <467bcffb$0$4305$9a566e8b_at_news.aliant.net>
>
>
> That's not how I would formulate it. Strictly speaking the attribute
> is a position or role in a predicate. So if the predicate is P(x, y)
> then there are two positions / attributes: the first position where x
> is bound and the second position where y is bound. It doesn't really
> make sense to say that the variable is the attribute because how then
> would you describe the situation in the formula "P(x, y) and Q(x, x)"?
> Is the variable 'x' an attribute? It makes more sense to say that it
> is a variable that is bound to the first position / attribute of P and
> the first and second posiiton / attribute of Q.
>
> So, er, I guess my previous answer should actually have been "no, not
> exactly". ;-)
Date: Fri, 22 Jun 2007 10:35:03 -0300
Message-ID: <467bcffb$0$4305$9a566e8b_at_news.aliant.net>
Jan Hidders wrote:
> On 22 jun, 14:25, Bob Badour <bbad..._at_pei.sympatico.ca> wrote:
>
>>Jan Hidders wrote: >> >>>On 22 jun, 01:36, Bob Badour <bbad..._at_pei.sympatico.ca> wrote: >> >>>>Jan Hidders wrote: >> >>>>>On 21 jun, 21:17, vldm10 <vld..._at_yahoo.com> wrote: >> >>>>>>On Jun 18, 7:41 pm, Jan Hidders <hidd..._at_gmail.com> wrote: >> >>>>>>>On 18 jun, 20:59, vldm10 <vld..._at_yahoo.com> wrote: >> >>>>[snip] >> >>>>>>>If this is a relation then >>>>>>>all columns are attributes and since you have represented all the >> >>>>>>Can you please, tell me what is the definition of the attribute in RM. >> >>>>>It's a column of a relation. Conceptually it represent the role in the >>>>>predicate that is represented by the relation. >> >>>>Is an attribute a predicate variable of some sort? >> >>>As in "the x in predicate P(x, y) "? Yes, I'd say that is the same >>>thing. >> >>I thought so. When one writes a query and requests certain attributes, >>would those requested attributes be free variables in a logic sense?
>
>
> That's not how I would formulate it. Strictly speaking the attribute
> is a position or role in a predicate. So if the predicate is P(x, y)
> then there are two positions / attributes: the first position where x
> is bound and the second position where y is bound. It doesn't really
> make sense to say that the variable is the attribute because how then
> would you describe the situation in the formula "P(x, y) and Q(x, x)"?
> Is the variable 'x' an attribute? It makes more sense to say that it
> is a variable that is bound to the first position / attribute of P and
> the first and second posiiton / attribute of Q.
>
> So, er, I guess my previous answer should actually have been "no, not
> exactly". ;-)
Thank you, that clarifies things for me. Received on Fri Jun 22 2007 - 15:35:03 CEST