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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>
 
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> -----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 GMT

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