Re: [OEP] Draft of a note on n-ary relations

>>> - The property "amount" seems to me a Datatype property ...
>>> I would suggest to either get rid of it altogether ...
>
>> I favor getting rid of it. This would mean using something other than
>> purchase though (seems unnatural to define a purchasing event without
>> an amount -- yo are right it doesn't add anything and only creates the
>> confusion, but still). Perhaps borrowing or something like that.
>
> The original sentence defining the situation has to be corrected in 
> any case ...
>
> "John buys a "Lenny the Lion" book from Mary for $15 as a birthday 
> gift."
>
> Should read certainly
>
> "John buys a "Lenny the Lion" book for $15 *for* Mary as a birthday 
> gift."

Actually, it's me not using the right words again (see a pattern here? 
:) a different kind of one, I suppose).

What we actually had in mind was indeed that John buy the book *from* 
Mary for a birthday gift for someone. So Mary was the recipient of the 
$15. So, by trying to use the generic roles of "recipient" and "agent," 
we've obscured the issue. I guess it would be better to use simply 
"buyer" and "seller". We can still omit the amount not to get into that 
discussion or just mention it and cross-reference the forthcoming 
pattern on quantities.

I would still go with the purchase example as its slightly more 
straightforward than the gift one (on the gift side, one might wonder 
for example if Mary and Mary's birthday should somehow be connected, 
etc.)

> Mary should not know anything about the former, and certainly not the 
> amount - that would
> be considered as rude from John, at least in France, maybe not in 
> America, where $ is the
> measure of everything :))

no, don't worry, even in America you don't usually flaunt the price of 
your gift :)

> Another picky remark : the identification of the gift object is 
> somehow fuzzy here.
> Is it an individual copy, or the generic publication defined e.g. by 
> its ISBN number as
> discussed before?
> Accurately, it's a random instance of the publication, before the 
> purchase, and it becomes
> a singular, identified one as soon as it is signed up by John ("To 
> Mary, for her 7th
> birthday - John") and offered.
> Should the example capture that, or sweep the difficulty under the 
> carpet ?

I'd say sweep -- the difference in representing a physical copy of the 
book and a generic publication is certainly out of scope here.

Natasha

Received on Monday, 10 May 2004 20:01:41 UTC