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RE: Possible solutions for ISSUE 97

From: Hausenblas, Michael <michael.hausenblas@joanneum.at>
Date: Thu, 20 Mar 2008 08:21:11 +0100
Message-ID: <768DACDC356ED04EA1F1130F97D29852015C4E2A@RZJC2EX.jr1.local>
To: "Ben Adida" <ben@adida.net>, "Mark Birbeck" <mark.birbeck@x-port.net>
Cc: <public-rdf-in-xhtml-tf@w3.org>, "Dan Brickley" <danbri@danbri.org>

My 2c:

Looking at section '5.1 XML Content within an RDF Graph' [1] of the RDF
Concepts, IMHO two important statements are:

The lexical space is the set of all strings: 
-> for which encoding as UTF-8 [RFC 2279] yields exclusive Canonical XML
(with comments, with empty InclusiveNamespaces PrefixList ) [XML-XC14N];

The value space 
-> and in 1:1 correspondence with the lexical space. 

Further, the RDF Concepts mentions in section '6. Abstract Syntax
(Normative)' [2]:

'Implementation Note: This abstract syntax is the syntax over which the
formal semantics are defined. Implementations are free to represent RDF
graphs in any other equivalent form. As an example: in an RDF graph,
literals with datatype rdf:XMLLiteral can be represented in a
non-canonical format, and canonicalization performed during the
comparison between two such literals. In this example the comparisons
may be being performed either between syntactic structures or between
their denotations in the domain of discourse. Implementations that do
not require any such comparisons can hence be optimized.'

Hope this helps in our discussion, today.

Maybe also DanBri can shed some light on it?


[1] http://www.w3.org/TR/rdf-concepts/#section-XMLLiteral
[2] http://www.w3.org/TR/rdf-concepts/#section-Graph-syntax

 Michael Hausenblas, MSc.
 Institute of Information Systems & Information Management
 JOANNEUM RESEARCH Forschungsgesellschaft mbH

>-----Original Message-----
>From: public-rdf-in-xhtml-tf-request@w3.org 
>[mailto:public-rdf-in-xhtml-tf-request@w3.org] On Behalf Of Ben Adida
>Sent: Thursday, March 20, 2008 2:05 AM
>To: Mark Birbeck
>Cc: public-rdf-in-xhtml-tf@w3.org
>Subject: Re: Possible solutions for ISSUE 97
>Mark Birbeck wrote:
>> So however people reply to this view-point, they need to make some
>> reference to RDF Concepts, and say why my interpretation *of that* is
>> wrong.
>I think you're framing the problem incorrectly and torturing yourself 
>into more complexity than needed.
>But instead of writing another massive email, let me try to identify 
>where, in the logical flow, we disagree with one another.
>In your flow, here's where I disagree:
>>   (1) we run the RDFa parser on an input document,
>>   (*) the output of the RDFa parser is RDF
>>   (2) we take the output of the parser and stuff it into a 
>triple store,
>>   (3) we SPARQL against the triple store.
>Step (*) is imprecise, in my opinion; it mixes abstract and concrete. 
>The output of an RDFa parser is, IMO, *a serialization of an 
>RDF graph*. 
>That is the key difference, because the "RDF Concepts" definition of 
>XMLLiteral applies to the abstract graph, not to all of the graph's 
>valid serializations.
>Now, help me understand where you disagree with my reasoning. Here are 
>two RDF N3 *serializations*:
><> dc:title
>"<div xmlns="http://www.w3.org/1999/xhtml">
>   foo <b xmlns="http://www.w3.org/1999/xhtml">bar</b>
><> dc:title
>"<div xmlns="http://www.w3.org/1999/xhtml">
>   foo <b>bar</b>
>If I'm reading the XMLLiteral canonicalization process correctly, I 
>believe that the two examples above are serializations of the same RDF 
>Do you agree? If not, why not?
Received on Thursday, 20 March 2008 07:23:49 UTC

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