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Re: pfps-04 [RDF entailment rules not yet complete]

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Thu, 31 Jul 2003 16:06:17 +0100
Message-ID: <3F293069.8000808@hplb.hpl.hp.com>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
CC: www-rdf-comments@w3.org, phayes@ai.uwf.edu

Peter F. Patel-Schneider wrote:
> From: Brian McBride <bwm@hplb.hpl.hp.com>
> Subject: Re: pfps-04 [RDF entailment rules not yet complete]
> Date: 31 Jul 2003 14:23:01 +0100
> 
> 
>>Peter wrote:
>>
>>[[
>>I believe that the rules for rdf entailments are still incomplete in 
>>RDF Semantics (Editors [sic] Draft of July 27).
>>
>>For example, consider the RDF graph
>>
>>	ex:foo ex:bar "<ex/>"^^rdf:XMLLiteral .
>>
>>I believe that this graph rdf-entails
>>
>>	ex:foo ex:bar "<ex></ex>"^^rdf:XMLLiteral .
>>]]
>>
>>Is "<ex/>" a member of the lexical space of rdf:XMLLiteral?  I don't
>>think so: 
>>
>>http://www.w3.org/2001/sw/RDFCore/TR/WD-rdf-concepts-20030117/#section-XMLLiteral
>>
>>[[
>>The lexical space
>>        is the set of all strings which: 
>>              * are well-balanced, self-contained XML data [XML];
>>              * correspond to exclusive Canonical XML  (with comments,
>>                with empty InclusiveNamespaces PrefixList) [XML-XC14]
>>]]
>>
>>"<ex/>" does not correspond to exclusive canonical XML; it would have to
>>be "<ex></ex>".
>>
>>Brian
> 
> 
> I am unconvinced.  Just what does ``correspond'' mean here - does it mean
> ``are'' or does it mean ``resulting in ... when canonicalized''? 

Neither.  It means that if you encode the string using UTF-8 you get 
cannonicalized XML.  I'll check this on the WG list.

Thus "<ex></ex>" is in the lexical space, and "<ex/>" is not.

  I give it
> the second meaning, so that "<em></em>" is in the lexical space, but "<" is
> not.

I think your conclusions are right, your premise is not.

> 
> I note that the relevant pointers in RDF Semantics are still broken.  
> 
> I also note that if the first meaning is indeed correct, then much of the
> treatment of XML literals in RDF Semantics needs to be changed.

Oops - please can you say why.

Brian
Received on Thursday, 31 July 2003 11:07:41 GMT

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