[sc34wg3] Topic Maps land and SAM land

Jan Algermissen sc34wg3@isotopicmaps.org
Mon, 10 Feb 2003 19:38:30 +0100

Lars Marius Garshol wrote:
> * Michel Biezunski
> |
> | RDF proceeds with statements. It is directed. There is an origin and
> | an end. It's difficult in RDF to say something about the same given
> | subject involved in another statement because there is no built-in
> | solid mechanism to make these subjects the same.
> Uh? If the URIs are the same, RDF considers that the statements are
> referring to the same resource (subject). There's also machinery in
> both DAML+OIL and OWL for working out when different URIs represent
> the same thing, and even for working out when they must represent
> different things. So the situation compared to topic maps is that you
> have a stronger apparatus for declaring when things are the same, and
> in addition an apparatus for declaring when they can't be.

Hmm...one of the basic ideas of the RM is that it enables TM Models
(RM: Applications) to define whatever rules they need for declaring
subject equivalence. Why do you think that this is that not stronger
than what RDF provides?
> The similarity with between the RM and RDF goes as follows:
>  - subject (in RM) the same as resource in RDF,

No. Why do you say that?

>  - proxy (or node, or whatever RM calls them right now) is the same as
>    RDF node in RDF,

In what sense are they the same? The SLUO does not apply to RDF, so
I see quite a difference there.
>  - assertion in RM is the same as statement in RDF.

No, it is not. What part of the RM makes you think that?
> There are some minor differences with regard to how data values get in
> there (node properties in RM, literals in RDF) 

In what sense are node properties in RM similar to literals in RDF? 

> and a not-quite-so-minor
> issue with respect to reification, but that's really it. In all, the
> similarities are much greater than the differences, which is not the
> case if you compare RDF/SAM. RDF is lower-level than SAM, but pretty
> much at the same level as RM.

Hmm, I don't understand what part of the RM leads you to this assumption!?

The RM provides a framework for defining TM Models (such as the SAM for example)
and this is something very different to what RDF is.


> | RDF is built on a predicative logic in other terms.
> Not really. It's a graph. The logic layer is built on top of the
> graph. If you look at the RDF Semantics document you'll see that what
> it describes is a logic built on a graph syntax.
> | The fact that RDF is a graph and TM is expressed as a graph is a
> | side issue.
> True.
> | It's my impression that you are putting more focus on formalism than
> | on what is expressed.
> Not correct. I would have said the same thing had the RM or RDF been
> specified in terms of the infoset model, as in fact they can both very
> easily be. What I said was based on my analysis of RDF that I
> presented in Orlando, and which was the basis for the RDF->TM mapping
> that underlies Ontopia's autogen toolkit.
> | This is why I am advocating for getting to the proper level of
> | abstraction. Let's forget the formalism for a moment, and discuss
> | the content.
> I've been doing that all along.
> | If you do that, you'll see that RM *is* TM -- not in the sense that
> | it is "on the TM side" but it is what TM is. Same thing with SAM.
> | SAM *is* TM and actually reflects faithfully a number of
> | implementations of it.
> Yeah, I know you think this, but I don't.
> --
> 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