[sc34wg3] SAM: Topic Identity

Lars Marius Garshol sc34wg3@isotopicmaps.org
03 Jul 2003 13:50:28 +0200

* kal@techquila.com
| Rereading the SAM with CXTM glasses, I notice that the Topic
| information item does not require any form of identity. Each of the
| properties [source locators], [subject indicators] and [subject
| addresses] may be empty as can the [names] property.

I've been uneasy about this myself, and I do feel that it might be
that a topic should be required to have some form of identity. RDF
does not require this, but even so it would make life much easier for
upper layers (TMQL, say, as well as any other technology that uses
topic references) if this were required.

And, as you point out, there is no way in HyTM or XTM to create a
topic map that does not have an identity, so we wouldn't really be
adding a new constraint on the syntactical expression of topic maps.
| It seems to me that a Topic item should have at least one locator in
| the union of the [source locators] and [subject indicators]
| properties (this is certainly the case for models built from XTM and
| HyTM and I think from LTM too...I don't know about AsTMa).

You are right about LTM; we're in the same boat with regards to AsTMa=3D.

| Is it really intended that one should be allowed to create a topic
| map syntax that enables topics to be created with no identity at all?

Speaking for myself: yes. Was I happy with that? Not really.
| Hence one can always infer at least one value for the union of [source
| locators] [subject inidcators] and [subject addresses] properties.
| Shouldn't the SAM reflect this ?

I'm tempted to say that we should change it to add this constraint.
The only place this would conflict with is the processing of <member/>
elements in XTM, where we said that if no member was specified one
should be generated automatically. However, we can just require that
it have a random and unique source locator assigned.

I'd be very interested to hear what people think about this, however,
and I think perhaps we should make it an official issue to be
discussed at the Montr=E9al meeting.


Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
GSM: +47 98 21 55 50                  <URL: http://www.garshol.priv.no >