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RDFCore Update

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Mon, 05 Nov 2001 13:44:00 +0000
Message-ID: <3BE697A0.5010408@hplb.hpl.hp.com>
To: www-rdf-interest@w3.org
Some more decisions from the RDFCore WG.  Further information can be found in 
the issue tracking document:

   http://www.w3.org/2000/03/rdf-tracking/

The working group has now formally resolved that bNodes (formerly known as 
anonymous resources) are part of an RDF graph.

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.

The WG has also decided to close

     * rdfms-syntax-desc-clarity: The language describing the syntax is unclear.
     * rdfms-formal-grammar: A formal grammar for RDF.

since we are rewriting the syntax description using a new approach to defining 
the grammar based on infoset

and to postpone for a future version of the spec

     * rdfms-syntax-incomplete: The RDF/XML syntax can't represent an an
       arbritary graph structure.
     * rdfms-qnames-as-attrib-values: Suggestion that Qnames should be
       allowed as values for attributes such as rdf:about.
     * rdfms-qnames-can't represent-all-uris: The RDF XML syntax cannot
       represent all possible Property URI's.
     * rdfms-quoting: The syntax needs a more convenient way to express
       the reification of a statement.

As always if you you have any comments on these decisions, please send them to 
www-rdf-comments@w3.org.

Brian McBride
RDFCore co-chair
Received on Monday, 5 November 2001 08:49:05 GMT

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