[Zope3-dev] Re: Zope3-dev Digest, Vol 25, Issue 37

[Benji York]

Jean-Marc Orliaguet wrote:
> Benji York wrote:
>>Can you give an example of one of these pieces of knowledge?
> 
>     "John gives a book to Mary"

> If you store the relations "John drops the book" and "Mary picks the
> book" how will you know if the book belongs to Mary and belonged to John
> before it was given to her? You could add "the book belongs to John"
> "the book belongs to Mary", add some date information, add the fact that
> the action is a gift (reification), ... all the pieces still have to be
> put together. This will need to be interpreted in a language (or a query
> language that does unions, intersections, ..) that knows how to put the
> pieces together. The model is very verbose is not explicit at all.

I assume you mean "no combination of dyadic predicates using only John, 
the book, and Mary as subjects and objects".  If so, I agree.

We're drifting fatally off topic here, but: Just as there are some 
statements that cannot be expressed as dyadic predicates, are there also 
those which cannot be expressed as triadic predicates?

     "John gives a book to Mary in exchange for 5 euros"

If you store the relations "John gives a book to Mary" and "Mary gives 5 
euros to John" how will you know that the 5 euros were payment for the book?
-- 
Benji York
Senior Software Engineer
Zope Corporation