[topicmapmail] Re: Getty Art and Architecture Thesaurus On Line

[Kal Ahmed]

On Mon, 2003-09-01 at 17:31, Murray Altheim wrote:
> kal@techquila.com wrote:
> > 
> > Well, I would hope so. But there still remains the issue of whether it is
> > an error for a topic which is being used as a class to also be an instance
> > of a class. My feeling is that it is not an error, simply the result of
> > representing two different type systems in a single topic map (which may be
> > the result of merging two separate topic maps). But if its not an error,
> > and we all agree that its not an error, perhaps it would be best to say
> > that its not an error so as to avoid confusion. Or is this all just so
> > obvious that it goes without saying ?
> 
> I can't remember the term, but to constrain topic maps would be something
> like a category error, in application of a constraint at the wrong meta-
> level. What we've *really* been talking about are semantics at a knowledge
> modeling level, above the topic map level. If you note that the "semantics"
> supplied with XTM were *mostly* in the form of PSIs, where absent them XTM
> would be almost semantics-free, this is akin to RDF being similarly
> semantics-free, only gaining them in specific applications like OWL. SO
> in a sense what we've been talking about is an application layer on top
> of topic maps, a set of PSIs enabling a specific model. 

Absolutely, and I am talking about the PSIs (for class-instance and
subclass-superclass) that are part of ISO 13250. Fortunately, from what
I've heard from Lars Marius on this list, it sounds like the definitions
are there in the prose. Its something I'll be checking next time I
review the documents :)

Cheers.

Kal
-- 
Kal Ahmed, Techquila
Standards-based Information Management
e: kal@techquila.com
w: www.techquila.com
p: +44 7968 529531