W3C home > Mailing lists > Public > public-sw-meaning@w3.org > March 2004

Re: Self-descriptive assertions

From: Mark Baker <distobj@acm.org>
Date: Fri, 26 Mar 2004 12:46:46 -0500
To: Bijan Parsia <bparsia@isr.umd.edu>
Cc: public-sw-meaning@w3.org
Message-ID: <20040326174646.GM11976@markbaker.ca>

On Fri, Mar 26, 2004 at 11:25:08AM -0500, Bijan Parsia wrote:
> >Yes, exactly.  That's what I mean by "communicate the graph".  If I
> >use text/plain, I'm not communicating the graph, because the message
> >doesn't include any information would inform a recipient that the
> >message semantics depend on the RDF specs.
> This is a total non-starter, IMHO. It doesn't work either way: I don't 
> necessarily "communicate the graph" by using application/rdf+xml (think 
> about a tutorial on the hidiousity of RDF/XML), nor do I necessarily 
> *fail* to "communicate the graph" by not using it.

I'm quite certain that you do, in both cases.

> Note that by your model, there's no way to "communicate" an owl 
> ontology (since we don't have an owl mimetype).

But is an OWL ontology any more than an RDF graph?  AFAIK, it isn't.
So you don't need a new media type.  I fully agree with DanC's
assessment here;


> >>Now, the sender _may_ be wanting you to think "Yea, verily, this
> >>information is true, and I _am_ expecting everyone to apply RDF
> >>interpretation rules to it", but there are many other possibilities.
> >
> >Yup.
> Hence you can't infer things *either way*. I.e., you can't assume that 
> the sender *didn't* want her text/plain to communicate the graph.

I don't see how that follows.  Perhaps I misunderstood Thomas.

I understood "possibilities" to mean possibilities for processing.
If he meant possibilities for interpretation of semantics, then I
disagree.  Ambiguity in message semantics is really bad thing.

> Mimetypes don't tell use a lot about content, actually. Imagine a gif 
> of an rdf graph. That might well communicate the graph! Why not? (e.g., 
> I have an ocr program)

If we're just talking about automata here, then no, the graph is not
communicated, because the recipient can't "follow your nose" from any
information in the message to any specification which says the graph is
being communicated.  You either need a new media type (image/rdf+gif?)
or out-of-band agreement between the parties for that to happen.  But
for an Internet scale system like the Web, I consider the latter a

Mark Baker.   Ottawa, Ontario, CANADA.        http://www.markbaker.ca
Received on Friday, 26 March 2004 12:39:23 UTC

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