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Re: LANG: A proposal for the layering problem

From: Dan Connolly <connolly@w3.org>
Date: 25 Mar 2002 09:24:35 -0600
To: Jonathan Borden <jonathan@openhealth.org>
Cc: Jeff Heflin <heflin@cse.lehigh.edu>, WebOnt <www-webont-wg@w3.org>
Message-Id: <1017069876.6568.20.camel@dirk>
On Sat, 2002-03-23 at 04:26, Jonathan Borden wrote:
> Dan Connolly wrote:
> >
> > I'm not sure I really like this, but I know I prefer
> > it to the same-syntax-different-semantics approaches.
> >
> > i.e. in this approach, if you mean something
> > different, you say it a different way.
> >
> > I would find it completely unacceptable if
> > two different W3C recommendations gave
> > different meanings to the same document.
> >
> 
> I am glad you have this "meaning" thing figured out better than I do. I
> think you are rather close to constraining us into a position that we will
> not like. For example: the RDF/XML conversion of N3 uses the
> rdf:parseType="log:quote" to contain contexts. To N3 these contexts contain
> statements, to RDF/XML the "log:quote" looks like literal XML.

Yup; it's broken. log:quote was supposed to be using
some syntax not used up by the RDF specs, but in
fact the RDF specs _do_ say that parseType="log:quote"
gets treated like parseType="Literal", which is
inconsistent with the way cwm does things.

> I am not
> suggesting that this be the final solution to the problem, on the otherhand
> _some day_ you may wish to formalize N3 (perhaps SWLL etc.) into a W3C
> recommendation. I hope that the "meaning" of such documents will not be
> constrained by today's RDF.

How could it be otherwise? If there are bzillions of "today's RDF"
consumers out there that understand the meaning one way,
there's nothing I can put in a spec to change that.

> When RDF 2 comes along is RDF 1 retracted?

That depends on a lot of things.

If RDF 1 and RDF 2 intersect, then the meaning given
by RDF 2 to the intersecting documents
will have to be consistent with the meaning
given by RDF 1.

> Will the 'meaning' of RDF 1
> documents change? A simple example (insert well know namespace decls)
> 
> <rdf:RDF>
>     <rdf:Description ID="foo">
>         <prop xmlns="http://example.org/ex">bar</prop>
>     </rdf:Description>
> </rdf:RDF>
> 
> will this document 'mean' the same under the current RDF recommendation, as
> with the hopefully soon to be released revision?

I don't think I understand the question.


> Not to be difficult, but we need to be reasonable. It has not bothered me
> that the 'meaning' of an RDF vs. an OWL document might be different: The
> true meaning of an OWL document should only be known to an OWL processor.

Ah.. I misspoke: I meant that it would be unacceptable if
different recommendations gave *conflicting*, i.e. *inconsistent*
meanings to the same document. It's all very well if
one of them just tells you more about the document.

> RDF holds the syntax in triples, but the meaning of OWL is in the Classes
> and Properties of the OWL language. How could it be otherwise?
> 
> Jonathan
> 
-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Monday, 25 March 2002 10:24:38 GMT

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