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Re: The X Datatype Proposal

From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Date: Wed, 14 Nov 2001 14:47:50 +0000
Message-Id: <>
To: Patrick.Stickler@nokia.com
Cc: w3c-rdfcore-wg@w3.org

I've taken a look through your "X datatype" proposal, and I regret to say 
that I cannot see how it really helps to address the literal datatyping issue.

Maybe I'm being dumb, but as far as I can tell the basis of your proposal 
is to describe *every* statement in a RDF graph by a structure using 
subject/object/predicate properties (i.e. the structure called 
"reification" in the original M&S document).

This means that a statement that ascribes a type to a literal can do so by 
using a subject property to reference the literal value, as in (using N3):

     [ a rdf:Statement ;
       rdf:subject "10" ;
       rdf:property rdf:type ;
       rdf:object  xsd:integer ]

This seems to me like a rather long-winded way around what Pat is proposing 
to allow (as a legitimate inference, if not in the RDF/XML syntax), namely 
literals as subjects:

     "10" rdf:type xsd:integer .

just seems like an order of magnitude simpler to me.

And there are still all the issues of how to construct a formal semantics 
(preferably a model theory) for your proposal, which you haven't started to 
do.  Pat's proposal has gone a long way down this path.  I strongly suspect 
that when you do the same for your proposal you would end up with something 
that really isn't so different in its ability to express data types, but 
vastly more complicated to express by virtue of being attached to a more 
complex syntax.

Finally, I think there are some aspects of your proposal that would prevent 
it from describing some aspects of legal RDF as currently defined (notably 
the distinction between subject nodes and nodes with URI labels).  This 
could probably be fixed by I really don't see that it would be worth the 

I'm sorry to be so negative, but unless I'm missing a key point I can't see 
that this really adds anything to what we've already achieved.  (Hint:  if 
you think I am missing a key point, note that Pat has been able to sketch 
his basic ideas in less than, or about, a page of text;  if you your key 
ideas likewise cannot be likewise distilled I'm going to have a really hard 
time accepting that they are any better that what we already have.)


Graham Klyne                    MIMEsweeper Group
Strategic Research              <http://www.mimesweeper.com>
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Received on Wednesday, 14 November 2001 09:53:18 UTC

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