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Resolution of: #rdfms-identity-anon-resources

From: Graham Klyne <GK@NineByNine.org>
Date: Wed, 10 Oct 2001 16:23:05 +0100
Message-Id: <>
To: RDF core WG <w3c-rdfcore-wg@w3.org>
[Re-post, with comments to specific issues raised in the original issue -- 
see end of this message.  I've also re-phrased point 3 to avoid the phrase 
"normal use".]

With respect to the issue:
[1] http://www.w3.org/2000/03/rdf-tracking/#rdfms-identity-anon-resources

Being a revision of my previous message:
[2] http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Aug/0030.html

And citing the model theory document:
[3] http://www.w3.org/TR/2001/WD-rdf-mt-20010925/

I propose the following resolution text:

1. 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.

2. 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.

3. 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 [3], section 2.  See also the anonymity 
lemmas in section 3.2.

NOTE:  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.

This resolves specific questions in the original issue raised thus:

[1.] Should anonymous resources have URI's?
-- No (point 1 above).

[2.] If so, should they be clearly distinguishable as parser generated URI's?
-- Not applicable:  the parser is not required to generate URIs.

[3.] Should there be a standard algorithm for generating URI's which ensures
  that different parsers generate the same URI's from the same source
  input document?
-- No:  the parser is not required to generate URIs.

[4.] How might these automatically generated URI's be affected by changes
  in the source document?
-- There no automatically generated URIs to be affected.


Graham Klyne
Received on Wednesday, 10 October 2001 12:25:39 UTC

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