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Re: rdf:li outside of rdf:Bag

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Tue, 22 Apr 2003 11:46:44 +0100
To: jimbobbs <jimbobbs@hotmail.com>
cc: www-rdf-interest <www-rdf-interest@w3.org>
Message-ID: <18755.1051008404@hoth.ilrt.bris.ac.uk>

>>>Jimmy Cerra said:
> 
> What does it mean to have an rdf:li element placed as the child of an
> element that isn't a collection element (rdf:Bag, rdf:Seq, rdf:Alt, or
> others)?  For instance, consider the following document:
> 
> <?xml version="1.0"?>
> <!DOCTYPE rdf:RDF [
> <!ENTITY jfc  "jfc://example#">
> <!ENTITY rdf  "http://www.w3.org/1999/02/22-rdf-syntax-ns#">
> ]>
> <rdf:RDF xmlns:jfc="&jfc;" xmlns:rdf="&rdf;">
> 	<jfc:arc rdf:about="#L1">
> 		<jfc:arcrole rdf:resource="#L1role" />
> 		<rdf:li>
> 			<jfc:Thing rdf:about="#t0" />
> 		</rdf:li>
> 		<rdf:li>
> 			<jfc:Thing rdf:about="#t1" />
> 		</rdf:li>
> 		<rdf:li>
> 			<jfc:Thing rdf:about="#t2" />
> 		</rdf:li>
> 	</jfc:arc>
> </rdf:RDF>
> 
> According to the W3C's RDF Validator (http://www.w3.org/RDF/Validator/),
> the above example parses without errors; however, I am skeptical of that
> validation.  What does the document mean?

The W3C RDF validator will validate any well formed namespaced-XML as
valid "RDF", even when it has no RDF/XML in it.  So take care.

Validation means the syntax is OK - there is no way at all it can
check that what you wrote makes sense for every RDF graph.  In this
case your syntax is OK.  

It looks likely that you "mean" the rdf:arc to be some kind of
container.  You could chose to add some rdf vocabulary that made that
description such as
  jfc:arc rdfs:subClassOf rdfs:Container
but what kind of container would be up to you, and other apps
wouldn't be able to tell much from that using just RDF/S terms.

Some things can be checked if you use an RDF schema-aware system and
assume that you have a closed world.  There are several of these
kinds of system such as Sesame and VRP.  The emerging OWL validators
might also be useful - an OWL Full validator will help you with RDF.
OWL would also allow you to say more about what an jfc:arc was.

> P.S. Also, does anyone know if rdf:about or rdf:resource are compatible
> with the xlink specification?  That is, can I link to and from nodes and
> arcs in RDF/XML graphs with xlink attributes?  Is there a concise way of
> doing it if so?

I think I covered that in my other mail - no they are not for what
you want, very likely.

Dave
Received on Tuesday, 22 April 2003 06:47:42 GMT

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