[sc34wg3] Topics that represent other topics?

[Steve Pepper]

* Martin:

> Saying that I am the father of
> that child or the child of that father is meaningful. What I still hope for
> is that I can reify both an association and my role in the association to
> form a single topic (parent-child/father and parent-child/son). At present I
> don't think I can do this with TMDM.

* Patrick:

| If there was an answer from the TMDM editors to your question I missed it.
| Could someone point to the answer in the archive or post an answer?

I don't think you missed anything. Let me have a stab on behalf of
the editors. (Note: In the following I am using "reify" and "reification"
in the sense defined in CD-13250-2, a.k.a. TMDM.)

The answer, Martin, is that you can't do this with TMDM. My question,
however, is why ever would you want to? The role played by a topic in a
particular association is always unique to that association. Therefore
it is sufficient to reify the role. There is no need to reify the
combination of association plus role.

Let us assume you have a daughter called Jenna. The structure of the
association representing your relationship with Jenna would be as
follows:

   Martin --- R1 --- A1 --- R2 --- Jenna

Each of these five "objects" would likely be typed. Thus, Martin
and Jenna could be topics of type "person"; R1 could be a role of
type "father"; R2 a role of type "daughter"; A1 an association of
type "parent-child".

Now, in order to make assertions about your role as father in this
relationship, you simply have to reify R1. In XTM you would do that
by creating a topic that references the corresponding <member>
element as subject indicator. There is no need to additionally
reference the association A1, because R1 only "exists" in the
context of A1.

Let us now assume that you have a second daughter, Barbara:

   Martin --- R3 --- A2 --- R4 --- Barbara

Your role as father in this relationship is a *different* role
(hence I call it R3 rather than R1). Those two roles are of the
same *type* ("father"), but they are still distinct from each other.
You can thus reify your role as father of Barbara separately from
the reification of your role as father of Jenna. There would be
two distinct topics representing those two distinct roles.

Given the above, why would you want to "reify both an association
and my role in the association to form a single topic"?

Curious of Oslo

--
Steve Pepper <pepper@ontopia.net>
Chief Strategy Officer, Ontopia
Convenor, ISO/IEC JTC 1/SC 34/WG 3
Editor, XTM (XML Topic Maps 1.0)