[Zope3-dev] Yet Another Relations (aka Reference) Engine...

[Helmut Merz]

Am Samstag, 12. November 2005 23:13 schrieb Jean-Marc Orliaguet:
> Helmut Merz wrote:
> >Maybe there is a better word for this kind of 'relation'?
> >
> >Helmut
>
> I don't know. I think you have to start from a definition that
> is not dependent on zope in general and understand what the
> concepts mean outside the computer world. This was not
> invented here.
>
> The "relations" used in software are more than just relations
> since they also assert something, and a relation by itself
> asserts nothing, it is just an abstraction that connect
> several things or aspects of things. So "relations" here are
> rather "propositions".
>
> for instance:
> "A blue box" involves a relation between the "box" and the
> quality "blue", but to represent the relation, you would to
> assert a proposition:
>
>     "The box is blue"

Thanks for the clarification, and I think I got it - though I 
have to admit that I got the feeling that my brain is not really 
built to work with formal logic in a practical way ;-)

So my suggestion would be to go the pragmatic way an just keep 
the word "relation" for representing the assertion of such 
propositions in software.

I'll be going to write a Zope 3 proposal on on the relation 
management stuff (in the first step only on the interfaces 
trying not to talk about implementation issues) and would gladly 
expect your comments then...

I think we cannot alway avoid words defined in another problem 
domain in a different way, which may be problem especially if 
the problem domains are related (like formal logic and computer 
science); but I'd care not to use a nomenclature that might 
confuse or mislead people knowing more about some stuff than me.

Anyway, what we are talking about are not "references".

> The proposition can be analysed. It has a predicate and a
> subject (or subjects if taken individually), the subject is an
> ordered tuple and the predicate is what is left of the
> proposition when the subjects have been removed (it is what is
> "predicated", or asserted of the subjects of the proposition)
>
> for instance in the proposition:
>
>     "The box is blue"
>
> the predicate "__ is blue" predicates "blueness" of the box
>
> but a predicate is not the same thing as a relation

Yup - I'm at the moment using the word "predicate" to signify a 
type of a relation (using it as a homonym to "relationship") 
though I'm again not sure if this might be plainly wrong or at 
least confusing.

Helmut