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Re: [ALL] [HTML] reification in rdf/a

From: Ben Adida <ben@mit.edu>
Date: Fri, 9 Dec 2005 13:03:52 -0500
Message-Id: <92BE377F-1292-4B9F-BA6C-B8FFDABE933F@mit.edu>
Cc: SWBPD list <public-swbp-wg@w3.org>, public-rdf-in-xhtml-tf@w3.org
To: Dan Brickley <danbri@w3.org>


Dan,

Thanks for this point, and apologies for my delayed response.

Is it the sense of the Working Group that reification is, itself, not  
a Best Practice for RDF?

I ask because your concern seems to be a generic concern about  
reification, not one about RDF/A's implementation of it specifically.  
So far, we've tried to build as much of RDF as possible into RDF/A,  
without prejudice as to which feature we implement, other than the  
inherent limitations of trying to express RDF in XHTML with as much  
simplicity as possible. To forgo reification for the reason below  
would be a slight departure from our approach to date: it would mean  
that we think the concept of reification is, itself, not a best  
practice and thus not a practice we want to encourage with a compact  
RDF/A reification notation.

Thus, I'm wondering if this belief -- that reification is generally  
bad news -- is widespread within the working group.

-Ben

On Nov 4, 2005, at 12:53 PM, Dan Brickley wrote:

>
>
> 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, 9 December 2005 18:06:21 GMT

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