W3C home > Mailing lists > Public > www-rdf-interest@w3.org > April 2002

RE: Explicit Disambiguation Via RDF bNodes, more Process

From: Bill de hÓra <dehora@eircom.net>
Date: Sat, 27 Apr 2002 10:32:38 +0100
To: "'Joshua Allen'" <joshuaa@microsoft.com>, "'Danny Ayers'" <danny666@virgilio.it>, "'Sandro Hawke'" <sandro@w3.org>, <www-rdf-interest@w3.org>
Message-ID: <000501c1edce$797744f0$887ba8c0@mitchum>
Hash: SHA1

> -----Original Message-----
> From: www-rdf-interest-request@w3.org 
> [mailto:www-rdf-interest-request@w3.org] On Behalf Of Joshua
> Allen 

> Danny Ayers:
> d) Or I could find a way to talk about the company without 
> having to know it's URI, by relating it to the URI that I *do*
> know. 
>> Joshua Allen:

 Since I am a concerned and civic person, I take approach "d".
 I could take two assertions:
http://www.microsoft.com/ isOwnedBy x
x hadIncome lots

Since I know that the *object* of the first assertion is the same
"thing" as the *subject* of the second assertion, it really doesn't
matter what URI they have, so long as it is identical and unique
(in other words, an anonymous node in N3 or RDF).

I don't understand. What _is_ 'x'? Is it a bnode, a uriref? It
matters; for example you can't just merge two bnodes together,
merging [1] from the RDF MT:

Notice that unlabeled nodes are not identified with other nodes in
a merge, and indeed this reflects a basic principle of RDF graph
inference: in contrast to urirefs, which have a global identity
which carries across all graphs, blank nodes should not be
identified with other nodes or re-labeled [sic] with urirefs, in
order to ensure that the resulting graph is entailed by what one
starts with. 
there is no valid RDF inference process which can produce an RDF
graph in which a single unlabeled node occurs in triples
originating from several different graphs. (Of course, such a graph
can be constructed, but it will not be entailed by the original
documents. It must reflect the addition of new information about
the identity of two unlabeled nodes.)
]]] [2]

This operation is sometimes called 'smushing'.

Bill de hÓra

[1]< http://www.w3.org/TR/rdf-mt/#defmerg >
[2]< http://www.w3.org/TR/rdf-mt/#entail> look for subheadings,
"Merging lemma" and "Anonymity lemma 2"

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Received on Saturday, 27 April 2002 05:39:51 UTC

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