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Re: lcsh.info RDFa SKOS and content negotiation - use of RDF-style # IDs in RDFa?

From: Steven Pemberton <steven.pemberton@cwi.nl>
Date: Fri, 03 Oct 2008 15:47:02 +0200
To: "Williams, Stuart (HP Labs, Bristol)" <skw@hp.com>, "Dan Brickley" <danbri@danbri.org>, RDFa <public-rdf-in-xhtml-tf@w3.org>, "www-tag@w3.org WG" <www-tag@w3.org>
Cc: "Ed Summers" <ehs@pobox.com>
Message-ID: <op.uiga8ofhsmjzpq@acer3010>

On Tue, 30 Sep 2008 18:16:34 +0200, Williams, Stuart (HP Labs, Bristol)  
<skw@hp.com> wrote:

> Only parially. *iff* the primary topic node were not blank, but a  
> definite URI node, then merging would world provided that equivalent  
> nodes were involved.
>
> However, the identity of blank nodes is scoped only to the graph that  
> they are in. If you have the two graphs:
>
> {
> _:StevenPemberton foaf:isPrimaryTopicOf <http://www.cwi.nl/~steven/> .
> }
>
> {
> _:StevenPemberton foaf:isPrimaryTopicOf  
> <http://www.w3.org/People/all#steven> .
> }
>
> You cannot determine that they both named resources have the same  
> primary topic - so the blank topic node in this case is basically  
> useless establishing that what we have are different accounts of Steven  
> Pemberton.
>
> IIUC isPrimaryTopicOf is intended to establish the use of say  
> http://www.cwi.nl/~steven/ as a subject indicator for Steven Pemberton.  
> As a subject indicator the resource can only be a subject indicator for  
> one thing (hence inverse functional) - though there may be many subject  
> indicators for a given thing. So if we have the merged graph:
>
> {
>         ex1:StevenPemberton foaf:isPrimaryTopicOf  
> <http://www.cwi.nl/~steven/>, <http://www.w3.org/People/all#steven> .
>         ex2:StevenPemberton foaf:isPrimaryTopicOf  
> <http://www.w3.org/People/all#steven> .
> }
>
> We can deduce that ex2:StevenPemberton is owl:sameIndividualAs  
> ex1:StevenPemberton (might be owl:sameAs) from the inverse functional  
> nature of isPrimaryTopicOf.

I'm inclined to say "Well, of course", and I have to admit I still don't  
see the problem.

There are things in the world without URIs (or with URIs that I don't  
know).

I see the use of blanknodes in this way as an existential quantifier  
"There is a thing that...". Then of course if I say "there is a thing that  
is the principle topic of A" and "there is a thing that is the principle  
topic of B" they are not the same thing until I prove they are.

But if I say, in two different graphs "there is a thing that is the  
principle topic of A", then those two things are clearly the same, and so  
everything I say about that thing in the two graphs can be merged. It all  
depends how you ground your blank nodes really.

Best wishes,
Steven
Received on Friday, 3 October 2008 13:51:35 GMT

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