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RDF issue rdfms-identity-anon-resources

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Thu, 01 Nov 2001 14:12:35 +0000
Message-ID: <3BE15853.1050205@hplb.hpl.hp.com>
To: jonas@paranormal.o.se
CC: www-rdf-comments@w3.org
Jonas,

In

   http://lists.w3.org/Archives/Public/www-rdf-interest/1999Nov/0115.html

you raised an issue with the RDF specifications which was recorded in the RDF 
Issue tracking document as:

   http://www.w3.org/2000/03/rdf-tracking/#rdfms-identity-anon-resources

The RDFCore WG has resolved

   that the RDF model theory draft of 25 September 2001 
(http://www.w3.org/TR/2001/WD-rdf-mt-20010925/) adequately addresses the issue 
http://www.w3.org/2000/03/rdf-tracking/#rdfms-identity-anon-resources

   http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Oct/0405.html

Whilst the formal resolution refers to the new model theory WD, this might be 
summed up as:

---------

Resources that are described but not named in an XML serialization (by rdf:ID or 
rdf:about) are represented in an RDF abstract graph by nodes that do not have 
any associated URI. Such nodes, called bNodes (from blank nodes) are thereby 
distinguishable from other described resource nodes, which do have an associated 
URI-reference label.

To directly address the question of the issue: a so-called anonymous resource 
has no URI.

To reflect un-named descriptions in N-triples, local names must be introduced 
(i.e. of the form '_:name'). These names are not URIs, and their scope is the 
N-triples document in which they appear.

In the defined use of RDF to express ground facts, the meaning of bNode is to 
assert the existence of at least one resource which is the subject and/or object 
of properties as indicated by the graph. This is covered more formally by the 
Model Theory section 2. See also the anonymity lemmas in section 3.2.

It has been proposed that the RDF graph syntax can be used for form a query, in 
which bNodes may be interpreted as query variables. This resolution confirms 
that bNodes can be distinguished from other labelled nodes within the graph 
syntax, but is silent about if and how the graph syntax might be used to 
represent a query.
----------

A set of test cases illustrating the resolution can be found at:

   http://www.w3.org/2000/10/rdf-tests/rdfcore/rdfms-identity-anon-resources/

We hope that you will find this resolution satisfactory.  Please could you 
respond to this message, copying to www-rdf-comments@w3.org, whether this 
resolution does satisfy your concern.

Brian McBride
RDFCore co-chair
Received on Thursday, 1 November 2001 09:17:08 GMT

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