[sc34wg3] What do we mean by reification?

[Steve Pepper]

At 14:03 03.03.2003 -0500, Patrick Durusau wrote:
>Where I am lost here is the **The basic topic map model does not allow 
>this** portion. If a subject is anything whatsoever I want to talk about, 
>why are association occurrences and giving an occurrence a name excluded 
>from that ambit? (Is this a question of XTM syntax? That may be where you 
>are losing me.)

No, it's not a question of XTM syntax, it's a question of ISO 13250 Topic Maps.

In the topic map standard:

- associations cannot have occurrences,
- occurrences cannot have names,
- names cannot play roles in associations,
- etc.

Right?

The only way you can make an assertion about anything in topic maps is by 
creating a topic for it and then assigning characteristics to that topic.

Right?

That's all Lars Marius is saying. Surely that's Topic Maps 101? (Or has 
your head been completely turned by the RM ;-)

If you want to say something more about, say, the relationship represented 
by an association, you have to create a topic for it.

There is a technique - fairly well documented since XTM 1.0 - of using the 
source locator of a topic map object (e.g. the ID of an <association> 
element) as the value of a <subjectIndictorRef> in a <subjectIdentity> 
element. This is, in effect, saying that the subject of the topic in 
question is the relationship represented by the <assocation> element. SAM 
wants to call *this* process "reification" and distinguish it from the 
general, run-of-the-mill act of creating a topic.

I think that makes sense. There is a very real need for a special term that 
distinguishes these two cases and the SAM's usage *does* seem to accord 
with general practice in AI.

I believe we should adopt the SAM's usage and modify the way the term is 
used in RM. (Does the RM actually even need it?)

Anyone that insists on going with the (more general) RM usage should be 
prepared to suggest terms to use instead of 
reification/reified/reifier/reify where SAM needs them.

Steve

--
Steve Pepper, Chief Executive Officer <pepper@ontopia.net>
Convenor, ISO/IEC JTC1/SC34/WG3  Editor, XTM (XML Topic Maps)
Ontopia AS, Waldemar Thranes gt. 98, N-0175 Oslo, Norway.
http://www.ontopia.net/ phone: +47-23233080 GSM: +47-90827246