Re: RA with MV attributes

From: paul c <toledobythesea_at_oohay.ac>
Date: Sat, 20 Jan 2007 01:28:52 GMT
Message-ID: <ofesh.707375$5R2.47345@pd7urf3no>

David wrote:
> paul c wrote:
>

>>David wrote:
>>
>>>paul c wrote:
>>>...
>>>
>>>>I do think that once one has a definition it is important to proceed to
>>>>positioning it in the scheme of things, for example is this a physical
>>>>approach for storing two relations in one or is it an attempt to promote
>>>>three-valued logic or is it something else?
>>>
>>>
>>>I'm interested in both its logical and physical aspects.  It seems
>>>best initially to focus mainly on the logical.
>>>...
>>
>>I could entertain this if the motive were to formalize a physical
>>storage scheme.  But I don't see anything logical about presenting to a
>>user the inference that fred and bill own an empty set of cars that are
>>green

>
>
> That's an incorrect inference. That's not what a tuple means. If you
> have the tuple
>
> Names = {Fred, Bill}, Cars = {}, CarColour = {green}
>
> Then you are meant to read out propositions by taking the cross product
> of the sets. The cross product is of course empty.
> ...

Try telling that to a user who can see with his own eyes that the system is telling him that Fred and Bill stand in some relation to green cars and then explain to him that there is no relation in this case, because he is looking at something called a "join" that some other user created!   (Then he will ask you what does join mean and the boss in frustration will renew your contract for another year.)

p Received on Fri Jan 19 2007 - 19:28:52 CST