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Re: reification test case

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Mon, 04 Feb 2002 19:07:39 +0200
To: ext Dan Brickley <danbri@w3.org>
CC: Dan Connolly <connolly@w3.org>, Jeremy Carroll <jjc@hplb.hpl.hp.com>, Brian McBride <bwm@hplb.hpl.hp.com>, <jos.deroo.jd@belgium.agfa.com>, Brian McBride <brian_mcbride@hp.com>, RDF Core <w3c-rdfcore-wg@w3.org>
Message-ID: <B8848C7B.D23A%patrick.stickler@nokia.com>
On 2002-02-04 18:50, "ext Dan Brickley" <danbri@w3.org> wrote:

> On Mon, 4 Feb 2002, Patrick Stickler wrote:
> 
>> On 2002-02-04 17:23, "ext Dan Connolly" <connolly@w3.org> wrote:
>> 
>>> On Mon, 2002-02-04 at 07:12, Jeremy Carroll wrote:
>>>> My vote: no.
>>> 
>>> I vote yes.
>>> 
>>> This is what "triple" means, after all, no?
>>> if x=xx, y=yy, z=zz, then (x,y,z)=(xx,yy,zz), no?
>> 
>> But a bNode of type rdf:Statement is not a triple, it
>> is the reification of a triple to which can be added
>> additional knowledge such as authority, source, scope,
>> etc.
> 
> shall we say it is a 'description of' a triple? (avoiding the
> term 'reification' wherever possible strikes me as a useful strategy,
> at least while we're discussing rdf:Statement...)
> 
> compare this to a 'description of' a Book, or a person, or any other type
> of thing whose instances might be described using bNodes in an RDF graph.
> In each such case the properties we attach to the bNode correspond to
> properties of the specific individual thing (some book, some person, some
> triple...) described.

OK. I see your point.

>> Whether two reification bNodes describe the same triple
>> does not necessarily mean that other properties ascribed
>> to each of those bNodes individually apply to all bNodes
>> reifying the same triple.
> 
> Trying this again swapping 'triple' for 'person':
> 
> whether two [reification] bNodes describe the same Person
> does not necessarily mean that other propeties ascribed
> to each of those bNodes individually apply to all bNodes
> [reifying/describing] the same person.
> 
> I'm not sure this works.

Right. I agree that both bNodes refer to the same triple,
I was just not comfortable with treating them as if they
were the same "instance of reference" so to speak.

> Could you give me an example where we have two bNodes describing
> one-and-the-same Person and there are properties on one bNode that
> wouldn't be appropriately attachable to the other bNode.
> 
> Or is there someone special about describing triples that makes
> it importantly different from describing people or books?

I was a little thinking about a case where for each
reification bNode, you have properties for source,
authority, and scope, and you may wish to know
which combination of source, authority, and scope
go together.

If you simply merge the bNodes, then you loose that
distinction.

It's not catostrphic, but I was trying to understand
the necessesity.

That's why I gave the _:B and _:G examples. It seemed
that the equality of the statement reification bNodes
was a special case that wouldn't apply for all bNodes
that had some intersection of property/value pairs.

Patrick

--
               
Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: patrick.stickler@nokia.com
Received on Monday, 4 February 2002 12:07:54 EST

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