[sc34wg3] Topic Maps land and SAM land

Jan Algermissen sc34wg3@isotopicmaps.org
Tue, 11 Feb 2003 23:59:29 +0100

Lars Marius Garshol wrote:
> * Jan Algermissen
> |
> | [how many RM assertions per RDF statement]
> |
> | The answer is that it depends on the TM Model (RM: application).
> | More precisely it depends on the way how a certain model 'decides'
> | to interprete a certain syntax.
> This was what I thought, and I didn't really see how it could be any
> other way.
> | In the case of RDF it does not only depend on the syntax but also on
> | the semantics of the used namespaces but that is another issue.
> Now I'm curious. How does the semantics of the RDF statements affect
> how they must be modelled?

XML namespaces have certain semantics (consider Dublin Core) if we want to
capture the information in an RDF document we need to be able to interprete
the namespace semantics. If we don't do that, we would only be reproducing the
RDF graph and I can't see any reason to do that.



<rdf:Description about="http://www.w3.org">
  <dc:Title>The web page of the W3C</dc:title>

<rdf:Description about="http://www.w3.org">
  <foo:Director>Tim Berners Lee</foo:Director>

1) makes a statement about the Web resource ('the page')
   and this (for example) affects the semantics of the about
   atribute (it points to the URL as a subjectAddress)

2) Here we make statement about the Organization and -ooops-
   the URL is a subject indicator.

This is what RDF cannot do but we can do, so we should do it ;-)

> | The structure of an assertion is explained in the RM prose. The mapping
> | from a given syntax to corresponding assertions is entirely part of the
> | definition of a TM model.
> Right. So you *could* create a model where every RDF statement maps to
> a single RM assertion?

Right. If anyone would think that it makes sense to capture the semantics of RDF
she could define a TM Model for it. This model could indeed be used to process
RDF at the RDF level, just reconstructing the RDF graph in a TM engine. 
Basically I assume that every existing RDF engine would then be conformant to that

> | So, a SAM defined in RM terms would include a processing model for
> | XTM, saying how all the element's are to be interpreted.
> Why would it? SAM doesn't have XTM elements in it, so why would an RM
> model of the SAM have them?

See 5.1.4  (10)


"If the TM Application defines one or more interchange syntaxes,
 the procedures for constructing topic map graphs from instances
 of each syntax ("Syntax Processing Models"), and "node demander"
 rules that allow topic map graph nodes to be indirectly addressed
 by addressing their corresponding syntactic constructs."

> | Yes, see above. The author(s) of a syntax processing model of a TM
> | Model make that choice.
> Now I'm surprised again: why do you say "a syntax processing model of
> a TM"? Where does syntax enter the picture?

Syntax is used to transfer semantic nets (what TM applications have in their
internals when they are up and running) and I need a definition how to 
reconstruct the original information from the serialized from.

Does that help?

> --
> Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
> GSM: +47 98 21 55 50                  <URL: http://www.garshol.priv.no >
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Jan Algermissen                           http://www.topicmapping.com
Consultant & Programmer	                  http://www.gooseworks.org