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Re: RDF 2.0 proposal: contextual properties

From: Dan Brickley <danbri@danbri.org>
Date: Wed, 08 Aug 2007 17:41:38 +0100
Message-ID: <46B9F242.60706@danbri.org>
To: Bruce D'Arcus <bdarcus@gmail.com>
CC: Garret Wilson <garret@globalmentor.com>, Ivan Herman <ivan@w3.org>, Semantic Web <semantic-web@w3.org>

Bruce D'Arcus wrote:
> 
> Garret Wilson wrote:
> 
> ...
> 
>>> I really do not like this general move of turning everything into '2.0'.
>>>   
>>
>> Call it what you will---contextual properties is a feature that I need 
>> and I think would be useful. I was using "RDF 2.0" as a shorthand 
>> because of the complaints I had received for complaining about the 
>> current RDF---I was told basically to go propose a new RDF or shut up. 
>> So I chose the easier of the two... ;)
> 
> To me this is all a question of priorities. To me, what could use fixing 
> in RDF and related specs are:
> 
>     - dump reification

I dislike the existing reification vocabulary. But we can't rewrite 
history: those classes and properties are in use. Should we really make
http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate and the others be 
404? or at least not describe those terms in the main RDF namespace?

I'd be happy to see them depractated using OWL or other terminology, but 
I dislike the approach of pretending they never existed.

I'd be happy to see special-case treatement of the reification vocab 
dropped from all RDF syntaxes.

>     - normalize the RDF/XML syntax

I'm not sure this will do everything people hope. A lot of the variation 
in RDF comes from the nature of the data (loopy graphs, missing stuff, 
unpredictability that comes from extensibility). There are other 
strategies for dealing with some of that, eg. directories of commonly 
used SPARQL queries that capture multi-namespace use.

>     - allow literal lists in RDF/XML

I believe they're allowed, just verbose.

"have an appreviated form for literal lists" I guess?

>     - add support for querying lists to SPARQL
> 
> I think it'd also make sense to add named graph support to RDF/XML; 
> namely, an rdf:about attribute to the root rdf:RDF node (though should 
> probably be changed to rdf:graph).

I don't think the syntax needs changing for this?

Design 1: an attribute beginning with "xml"

<?xml version="1.0"?>
<rdf:RDF xmlg="http://example.com/example-xml-graph-1"
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:dc="http://purl.org/dc/elements/1.1/">
   <rdf:Description rdf:about="http://www.w3.org/">
     <dc:title>World Wide Web Consortium</dc:title>
   </rdf:Description>
</rdf:RDF>


Design 2: an attribute in the xml: namespace

<?xml version="1.0"?>
<rdf:RDF xml:graph="http://example.com/example-xml-graph-1"
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:dc="http://purl.org/dc/elements/1.1/">
   <rdf:Description rdf:about="http://www.w3.org/">
     <dc:title>World Wide Web Consortium</dc:title>
   </rdf:Description>
</rdf:RDF>

Design 3: inline assertions

<?xml version="1.0"?>
<rdf:RDF
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:dc="http://purl.org/dc/elements/1.1/">
   <rdf:Description rdf:about="http://www.w3.org/">
     <dc:title>World Wide Web Consortium</dc:title>
   </rdf:Description>
   <rdf:NamedGraph rdf:about=""
      rdf:graph="http://example.com/example-xml-graph-1" />
</rdf:RDF>




> 
> Finally, I've often seen suggestions we need support for provenance and 
> time baked into the model (who made a statement, and when is it valid) 
> beyond named graphs. That seems like it might be a good idea.

I'd suggest folk take a look at the work of the RIF WG here,

http://www.w3.org/TR/rif-core/
http://www.w3.org/TR/rif-ucr/
http://www.w3.org/2005/rules/wg/wiki/
http://www.w3.org/2005/rules/wg

While the motivations for the RIF work come from a different angle, and 
are only partly RDFist ... if the language turns out well, it should tie 
  into RDF, while perhaps having some "larger than RDF" side to it too, 
eg. possibility for non-binary relations, which could carry the kind of 
extras people sometimes ask for.

Also http://www.w3.org/2005/Incubator/urw3/charter is worth a look - 
that's an incubator group at W3C around uncertainty reasoning, ... ie. a 
source of use cases and implementation ideas close to this topic.

cheers,

Dan
Received on Wednesday, 8 August 2007 16:42:00 GMT

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