[sc34wg3] SAM-issue psi-generics (was: SAM-issue term-scope-def)

[Marc de Graauw]

[Bernard Vatant]

> Of course Marc is not a topic, we all know that, but M and M1 are, and
they are the ones
> who matter really for the model. Marc himself cannot be trapped in the
model, and he's
> very happy of that :))

Yes I am, thank you very much :-)

> > | 1.  'Marc has a name "Marc de Graauw" '
> > | 2.  'Marc has one wife'
> > | 3.  'Marc has two sons'
> >
> > Now, the topic "Marc" doesn't have a wife, so obviously 2. is a
> > statement about the subject, and not about the topic.
>
> But 2 is a natural language statement about the subject, it's not in the
model !


No. I made it quite clear when I introduced the example that this was a
Topic Map, and 'Marc' a topic id. The only reason I used an informal natural
language representation is that I always find the existing standards lacking
for presenting clear and concise examples (XTM: too verbose, HyTM: not much
better, LTM: no standard and no self-explaining tags).

I understand your point of view but I find the discontinuity you allow
between topics and subjects very strange. For the topic 'Marc' you would
allow two characteristic assignments:
- 'Marc' is an instance of class topic
- 'Marc' plays husband-role in marriage X (in which Y plays wife-role)

Now you do agree that I - the person - am not a topic, and you would
probably agree I am married to Y (at least if you had been present at the
occasion). So there are two quite different kinds of assertions you allow on
a topic: those that have a counterpart in the real world (the husband role)
and those that have no counterpart in the real world (the topicness). I
think that is going to be pretty confusing for a user browsing the Topic
Map. That person is simply going to see a couple of class-instance
relationships when she clicks on topic 'Marc':
- 'Marc' is a 'husband'
- 'Marc' is a 'topic'
(or something similar).

How is this Topic Map user going to know that I - the person - am a husband
but not a topic???

Your view is consistent, but Lars' view seems much simpler: we only allow
topic characteristic assignments which express facts about the subject the
topic represents. So instanceOf(topic) is not allowed on 'Marc', only on its
reification 'Marc-the-topic'. And the person browsing the Topic Map does not
get confused.

> The subject Marc-out-there, the topic M representing the subject Marc, and
the topic M1
> representing the subject M, are three different animals. Only the two
formal ones, M and
> M1, we have to care of in the model. All the point of making a model is to
be able to set
> formal assertions about formal objects, and forget about whatever subjects
they represent
> *are* or *mean*.

Well, yes and no. In the Topic Map itself the subjects won't appear, but in
a standard like SAM it makes sense to say something about the relation
between the Topic Map and the subjects.

> Of course topic maps are interesting for humans because they make sense
when being
> interpreted in terms of subjects in the real world, but that is true of
*any* model of the
> world, and it does not mean we have to make the subjects interfer with the
model. Maths
> are interesting for non-mathematicians because formal mathematical objects
like e.g.
> vectors can be interpreted as representing real world objects like e.g.
electromagnetic
> fields. But when you work with the model, you set and compute formal
relationships between
> formal objects using formal rules, and you don't let interpretation in
terms of subjects
> interfer with it. Maths, Physics and other sciences have taken centuries
to set that
> efficient methodology.

Maybe maths, but certainly not physics (and most other sciences). There you
look at the real world, make a model, compute a bit to make predictions, and
go back to the real world to do experiments and see if the predictions from
the model fit reality. So the interpretation in terms of subjects plays an
important role in physics. And I wouldn't  want to see it any other way in
Topic Maps. The relation with the real world is essential, it is not just a
model for computations. It is true that during the computing the
interpretation in terms of subjects is temporarily irrelevant, but computing
is just an intermediary phase, not the goal!

Marc