W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > May 2001

Re: action item on reification

From: Graham Klyne <Graham.Klyne@Baltimore.com>
Date: Fri, 25 May 2001 08:00:11 +0100
Message-Id: <5.0.2.1.2.20010525074613.040893b0@joy.songbird.com>
To: jos.deroo.jd@belgium.agfa.com
Cc: RDF core WG <w3c-rdfcore-wg@w3.org>
At 01:07 AM 5/25/01 +0100, you wrote:

>[...]
>
> >    @prefix rdf: <http//www.w3.org/1999/02/22-rdf-syntax-ns#>.
> >    @prefix a:   <http//description.org/schema/>.
> >      [ a rdf:Bag ;
>                    ^was a ]
> >        rdf:_1 [ a rdf:Statement ;
> >                 rdf:predicate  a:creator ;
> >                 rdf:subject    <http//www.w3.org/Home/Lassila> ;
> >                 rdf:object     "Ora Lassila" ] ;
> >        rdf:_2 [ a rdf:Statement ;
> >                 rdf:predicate  a:title ;
> >                 rdf:subject    <http//www.w3.org/Home/Lassila> ;
> >                 rdf:object     "Ora Lassila's home page" ] ] .
>                                                              ^added

Ooops!  Thanks.  My blind spot:  I was wondering why it froze the online N3 
checker.

>let's think about a USE of that bag of statements such as
>
>   @prefix rdf: <http//www.w3.org/1999/02/22-rdf-syntax-ns#>.
>   @prefix a:   <http//description.org/schema/>.
>   {<http//www.w3.org/Home/Lassila> a:creator "Ora Lassila";
>     a:title "Ora Lassila's home page"} :attrbutedTo "Ralph Swick".
>
>[...]

(I deliberately avoided using N3's {} syntax because it's its 
interpretation is in question.  For now, I'll assume you mean it to be an 
rdf:Bag of reified statements.)

The trouble with this that I see is that the rdf:Bag is attributed, not the 
statements in the bag.

> >    @prefix rdf: <http//www.w3.org/1999/02/22-rdf-syntax-ns#>.
> >    @prefix a:   <http//description.org/schema/>.
> >    [ a rdf:Statement ;
> >      rdf:predicate  a:creator ;
> >      rdf:subject    <http//www.w3.org/Home/Lassila> ;
> >      rdf:object     "Ora Lassila" ]
> >        rdf:truth "0".
>
>an alternative could be
>
>   @prefix rdf: <http//www.w3.org/1999/02/22-rdf-syntax-ns#>.
>   @prefix log: <http://www.w3.org/2000/10/swap/log#>.
>   @prefix a:   <http//description.org/schema/>.
>   {<http//www.w3.org/Home/Lassila> a:creator "Ora Lassila"} a log:Falsehood.
>
>and there is no problem to express those
>cases in an RDF/XML 1.0 compatible syntax
>and the semantics are quite working

Looks fine to me ...   The semantics may work, but let us be clear that 
these are *new* semantics added to RDF (in my case with a new property, in 
your case with a new class), not part of the core semantics.

The purpose of this example was to show the use of reification as a "hook" 
for adding new semantics.

#g


------------------------------------------------------------
Graham Klyne                    Baltimore Technologies
Strategic Research              Content Security Group
<Graham.Klyne@Baltimore.com>    <http://www.mimesweeper.com>
                                 <http://www.baltimore.com>
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Received on Friday, 25 May 2001 12:22:51 EDT

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