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

Re: Self-descriptive assertions

From: Bijan Parsia <bparsia@isr.umd.edu>
Date: Fri, 26 Mar 2004 11:25:08 -0500
Message-Id: <25E7F8CA-7F42-11D8-AEC8-0003939E0B44@isr.umd.edu>
To: public-sw-meaning@w3.org

On Mar 25, 2004, at 11:20 PM, Mark Baker wrote:

> On Thu, Mar 25, 2004 at 02:17:02PM -0500, Thomas B. Passin wrote:
>>> True, but why is that bad?  I believe it's because - as I said above 
>>> -
>>> that the recipient would believe that the sender is trying to
>>> communicate the graph.
>> But the whole point is that the sender has no say in how the recipient
>> chooses to process the representation.
> Right ...
>>  Maybe I want to get an example
>> of application/rdf+xml to illustrate an article I am writing.  Maybe I
>> want to extract certain information using xslt and never need to form
>> triples.  Maybe I want to apply some non-RDF processing as I build the
>> graph.  Maybe I want to somehow canonicalize the data and end up with 
>> a
>> different (but we hope equivalent) one.  Maybe I have a quad system 
>> and
>> want to load the RDF into quad statements.
>> Or maybe I want to do what you think I ought to do.
>> So the only area we can have a reasonable hope of working with here is
>> what the _sender_ may have wanted to communicate beyond the actual 
>> data
>> contained in the application/rdf+xml representation.
> 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.

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

> In both cases (application/rdf+xml and text/plain) there is no
> requirement that the recipient extract the graph, as that would be a
> requirement on processing.

I don't want to put a yicky requirement on senders either :)

>> 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.

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)

Bijan Parsia.
Received on Friday, 26 March 2004 11:25:59 UTC

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