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 15:59:57 -0500
To: Bijan Parsia <bparsia@isr.umd.edu>
Cc: public-sw-meaning@w3.org
Message-ID: <20040326205957.GN11976@markbaker.ca>

On Fri, Mar 26, 2004 at 01:05:00PM -0500, Bijan Parsia wrote:
> >  AFAIK, it isn't.
> >So you don't need a new media type.  I fully agree with DanC's
> >assessment here;
> >
> >http://lists.w3.org/Archives/Public/www-webont-wg/2002Oct/0162.html
> 
> Don't see how that helps with OWL. Quite the contrary.

Sorry, I don't follow.  Dan concludes there that OWL doesn't need it's
own media, and he does based on reasoning identical to my own (AFAICT).

Anyhow, I should add that I don't know OWL; my agreement with Dan was
purely a result of my agreement with the mechanism he used to come to
his conclusion.  More in the response to Peter ...

> >I understood "possibilities" to mean possibilities for processing.
> >If he meant possibilities for interpretation of semantics,
> 
> How can you separate the two?

Here's an example ...

A message sender might send some XHTML as application/xhtml+xml to a
service, and that service could, say, print the number of lines in the
file to a printer.  So even though the intended semantics of the sender
was "Here's some content to interpret per the XHTML 1.0 spec", the
recipient is free to treat it as plain text in order to count the
lines.

> > You either need a new media type (image/rdf+gif?)
> >or out-of-band agreement between the parties for that to happen.
> 
> Yep.
> 
> >But
> >for an Internet scale system like the Web, I consider the latter a
> >non-starter.
> 
> So we disagree.
> 
> There's also an Always/Usually issue. I think that Usually is fine, but 
> once you say Always then you've made your system way way way too rigid. 
> It's very hard to capture all the different implicit and explicit 
> agreements and understandings people come up with (sanely) and encode 
> in their programs. Hamfisting it just makes people either ignore your 
> restrictions or not use your system.

I agree with your general point, though I'd opt for something a lot
stronger than "usually" in this case since the value of the
architectural properties obtained by adopting such a constraint is so
great.  But if you believe that what we've been discussing is one of
those cases where out of band agreement is valuable, I couldn't
disagree more.

Mark.
-- 
Mark Baker.   Ottawa, Ontario, CANADA.        http://www.markbaker.ca
Received on Friday, 26 March 2004 15:56:45 GMT

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