[sc34wg3] Topics that represent other topics?

Martin Bryan sc34wg3@isotopicmaps.org
Mon, 30 Aug 2004 09:04:50 +0100

Patrick asked:

> Martin: Does that capture the question or have I made a mess of it?

Yes and No :-(

> Lars,
> In part of your exchange with Martin Bryan the following appears:
> Martin:
> > | [My confusion with this is that I still don't see how I can make the
> > | subject of my topic the fact that an association has been set up
> > | between something with this role and something with that role
> > | ... but hopefully someone will explain that in terms I can
> > | comprehend one day.]
> >
> Lars:
> > Actually, that's been discussed at length and the conclusion that was
> > reached in the end is that topic maps don't provide any machinery for
> > creating topics that represent other topics, either. So the answer is
> > that at present this is not explicitly supported. You can define a
> > convention for this yourself, and use TMQL to query it, but you really
> > will have to do stuff yourself.
> Are you seeing this as the same as the: prop-reifier-topic discussion?
> My unofficial notes from Baltimore, 2002, indicated:
> > 1.7. prop-reifier-topic
> >
> > Can reify anything except a topic. Not possible now because it implies
merging. with subjectIndicatorRef to refer to the topic. Using a resourceRef
to address an Association (biggest outstanding issue).
> >
> > Proposed Resolution Should topic items have a reifier property and the
answer is no. (Consistent with reification in general. See
term-subject-address-def for further discussion) Definition of reification
needs to be revisited. 3.4.4
> I don't see Martin's question as one of how to reify a topic.
> I think he is asking if he can have a topic for a subject, where the
> identity of the subject is defined in terms of other topics.
> That is to say that Martin's topic is not representing other topics, but
> a subject that makes reference to other topics as part of its identity.
> It is that subject that is being represented by Martin's topic and not
> topics that are part of its identity.

I was specifically targetting associations rather than topics because they
have different characteristics. In particular they have direction. The
discussion that is taking place on another thread re the parents of a child,
and the fact that their roles are different is an indication of the problem.
When talking about a relationship defined in an association you need to know
which direction you are travelling. My children are different from my
parents, but in both case the relationship between me and them is a
parent/child relationship. Saying that there is a parent/child relationship
between me and someone else is meaningless. 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.