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[ALL] [HTML] reification in rdf/a

From: Dan Brickley <danbri@w3.org>
Date: Fri, 04 Nov 2005 17:53:22 +0000
Message-ID: <436BA012.9030203@w3.org>
To: SWBPD list <public-swbp-wg@w3.org>
Cc: public-rdf-in-xhtml-tf@w3.org


I have a concern about RDF/A encouraging usage of the old RDF 
Reification vocab, eg. as in
http://www.w3.org/2001/sw/BestPractices/HTML/2005-rdfa-primer#id0x0382be98

<link about="" rel="cc:license"
      href="http://creativecommons.org/licenses/by-nc-nd/2.5/">
   <meta property="dc:date" content="2005-10-18" />
</link>

yields:

[ rdf:subject <>;
  rdf:predicate cc:license ;
  rdf:object <http://creativecommons.org/licenses/by-nc-nd/2.5/> ]
dc:date "2005-10-18" .

My concern is that this vocab (rdf:subject/predicate/object/etc) appears 
to be a quoting mechanism, but isn't. So it interacts with other RDF 
statements in a way that is likely to cause confusion.

Imagine in the data above that <> is <http://a.example.org/> (to avoid 
relative URIs confusing things)...

What inferences go through if we believe that (excuse the notation, not 
sure if this is turtle)

<http://a.example.org/> owl:sameAs <http://b.example.org/> .
<http://creativecommons.org/licenses/by-nc-nd/2.5/> owl:sameAs 
<http://creativecommons.org:80/licenses/by-nc-nd/2.5/> .

I think this gets us.....

[ rdf:subject <http://b.example.org>;
  rdf:predicate cc:license ;
  rdf:object <http://creativecommons.org:80/licenses/by-nc-nd/2.5/> ]
dc:date "2005-10-18" .

While in the current example, the "dc:date = 2005-10-18" claim might be 
true, I don't think it follows that all such attempts at reification 
will make sense given the interaction with OWL-powered identity reasoning.

For example,


<link about="http://z.example.com/" rel="cc:license"
      href="http://creativecommons.org/licenses/by-nc-nd/2.5/">
   <meta property="xyz:reviewerNotes" content="Dan reviewed this." />
</link>
 
...if there are a number of other things that are owl:sameAs 
http://z.example.com/  .... for which the reification statements might 
be inappropriate, depending on the semantics of the meta property.

Hope these hurried notes make sense,

Dan
Received on Friday, 4 November 2005 17:53:32 GMT

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