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Re: rdfs:Statement for Qualified Predictates

From: Richard Newman <r.newman@reading.ac.uk>
Date: Thu, 5 Aug 2004 14:55:26 +0100
Message-Id: <1AAE5D5B-E6E7-11D8-A3C5-000A957D9564@reading.ac.uk>
Cc: <www-rdf-interest@w3.org>
To: Matthew Leingang <leingang@math.harvard.edu>

Matthew,
   Supplementary to Graham Klyne's recommendation, which I second, 
reification doesn't mean necessarily using rdf:Statement.

   I would recommend the following:

:some-ownership :owningParty :me ;
                 :startDate :my20thBirthday ;
                 # any other properties of the ownership ...
                 :ownedItem   [a :Book; :isbn "0123456789012"] .

where owningParty and ownedItem have sensible inverses.

   You could do it by RDF quotation (using rdf:Statement), but that 
specifically doesn't assert what you're quoting. In your second example 
it is not "true" that you own the book, only that some statement exists 
which says that.

   Take as your example the traditional use of rdf:value:

:me weight :myweight .
:myweight :unit :kg ;
           rdf:value "75" .


   By the way, I've been keeping an interested eye on Books; RDF export 
would be a very cool feature indeed. I'm occasionally working on a 
bibliographic ontology, and I'll let you know if it ever gets done!

   Regards,
Richard

On 4 Aug 2004, at 21:42, Matthew Leingang wrote:
> How does one best put something like "I have owned this book since 
> August 1,
> 2004" in RDF?  Without the date I could just say
>
> :me foaf:owns [a book:Book; book:isbn "012345678"] .

<SNIP>

> of regular RDF triples.  It seems, then, that you can do this by 
> reifying
> the statement and adding whatever other properties & types you want:
>
> [a rdfs:Statement;
>    rdfs:subject :me;
>    rdfs:predicate foaf:owns;
>    rdfs:object [a book:Book; book:isbn "012345678"];
>    a ical:Vevent;
>    ical:dtstart "2004-08-01".]
Received on Thursday, 5 August 2004 09:56:41 UTC

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