W3C home > Mailing lists > Public > public-rdf-in-xhtml-tf@w3.org > October 2006

Re: Reification support in RDFa

From: Dan Connolly <connolly@w3.org>
Date: Mon, 16 Oct 2006 17:25:33 -0500
To: Elias Torres <elias@torrez.us>
Cc: public-rdf-in-xhtml task force <public-rdf-in-xhtml-tf@w3.org>
Message-Id: <1161037534.3303.107.camel@dirk>

On Mon, 2006-10-16 at 17:32 -0400, Elias Torres wrote:
> During today's meeting we were discussing our current support for RDF
> reification in our current syntax draft [1] which states:
> 
> [[[During subject resolution (which could be triggered by object
> resolution for a rev attribute), the processor may traverse up the DOM
> tree in search of an about  attribute. If a link or meta element is
> encountered before an about attribute is found, and if this link or meta
> element itself does not have an about attribute, then the subject (or,
> again in the case of rev, object) is resolved as the [RDF/A statement]
> represented by this link or meta  element.]]]

I'm not fond of specifying meaning of documents in terms
of behavior of software ("the processor may...") but the example
that followed makes it pretty clear what's going on; and what's
going on falls completely within RDF as specified in the 2004
Recommendations. The turtle output is completely ordinary RDF:

 <> cc:license <http://creativecommons.org/licenses/by-nc-nd/2.5/> .
 <> dc:creator "Mark Birbeck."  
 _:a rdf:type rdf:Statement .
 _:a rdf:subject <> .
 _:a rdf:predicate cc:license .
 _:a rdf:object <http://creativecommons.org/licenses/by-nc-nd/2.5/> .
 _:a dc:creator "Ben Adida" .


> The main discussion point was who are the folks (such as IPTC and others
> from HTML WG) asking for reification and what the real requirement is
> for RDFa. Additionally, I brought up the point that the reification [2]
> vocabulary is not either clearly defined, implemented or used today and
> that we must be careful on taking on such a task.

I think it's reasonably well defined. It does not meet quoting
requirements, but the example in this RDFa draft doesn't involve
real quoting.


>  Reification in RDF M&S
> leans towards identification of statements as opposed to quotation [3].
> It's not clear which one we want in RDFa.

I don't see anything that suggests you want quotation. What
am I missing?

> I'd like for us (everyone) to discuss more how do we really want to
> approach reification in RDFa, especially since we have a better
> situation due to us dealing with HTML documents. We have documents being
> published on the web at specific locations and I think we have different
> two major ways to frame the issue/requirement. We might want to track
> provenance at the HTML/element level (e.g. who wrote what piece of HTML)
> vs at the RDF level (who said which triple). I think one option is for
> us to establish our purpose and provide a specific vocabulary to do so
> without dragging the whole use/mention, bnodes, named graphs issues
> attached with RDF reification and the communities trying to resolve it.
> 
> Any thoughts?

The relevant requirement for me is that RDFa be convertible to RDF/XML;
i.e. no more expressive. Real quoting would involve going beyond
the existing expressive capability of RDF/XML.

But I don't see anybody arguing for that.

> -Elias
> 
> [1]
> http://www.w3.org/2001/sw/BestPractices/HTML/2005-rdfa-syntax#id0x01cc64a0
> [2] http://www.w3.org/TR/rdf-primer/#reification
> [3] http://ioctl.org/rdf/usementionmyarse
-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Monday, 16 October 2006 22:25:43 GMT

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