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Re: RDF 2.0 proposal: contextual properties

From: Ivan Herman <ivan@w3.org>
Date: Wed, 08 Aug 2007 10:36:55 +0200
Message-ID: <46B980A7.4080700@w3.org>
To: Garret Wilson <garret@globalmentor.com>
Cc: Semantic Web <semantic-web@w3.org>
Garret,

I know I will get on your nerve with my remark; my apologies, it is not
my intention, really. But I would still like to be pedantic here. Are
you talking about

- an extension/change of the RDF core semantics, or
- some sort of a design pattern, possibly backed up by some syntactic sugar?

I think it is very important to differentiate between the two. An new
serialization syntax (or extension of an old one), with possibly some
syntactic help for some design patterns is (though clearly a
not-always-simple engineering task) a much simpler issue than changing
the core RDF semantics, with all the possible effects on existing RDF
systems and deployment. Clearly, the latter requires _much_ more care.

My feeling is that you are talking about the former. But I am not sure,
could you elaborate on what construction it would be in general?

As an example, your example on xml:lang is clearly a _syntax_ issue and
not semantics. The RDF semantics document assigns language information
to one specific literal in:

http://www.w3.org/TR/rdf-mt/#interp

and that is it. There is _no_ context there. What you refer to in:

> 
> But RDF already includes one contextual property
> that behaves exactly as I'm describing: xml:lang. The xml:lang
> pseudo-property can appear "on any node element or property element",
> according to
> <http://www.w3.org/TR/rdf-syntax-grammar/#section-Syntax-languages>. The
> semantics of xml:lang seems to be, "This resource has the specified
> language---but only in the context of the given property." 

is merely an artefact of _a special serialization_, namely RDF/XML,
borrowing the features and behaviour of xml:lang from XML.

In other words, your statement:

> 
> Obviously xml:lang is a hack in the RDF model for a single case, forcing
> the model to carry around language information that isn't a real
> "property". 

is, I am sorry to say, erroneous. The artefact has nothing to do with
the RDF model.

Again, sorry to be so pedantic, it is not my purpose to be dismissive by
_any_ means. I would just like to understand what exactly your purpose
is and to formalize it accordingly...


<completely-side-issue>
I really do not like this general move of turning everything into '2.0'.
The current RDF does not have a number, so something like RDF 1.x does
_not_ exist... It makes me feel obliged to invent/call myself
Ivan_Herman 2.0, because Ivan_Herman is so passé... (well, if it was
that easy:-)
</completely-side-issue>


Thanks

Ivan

-- 

Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf


Received on Wednesday, 8 August 2007 08:36:56 GMT

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