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Re: A triple is not unique.

From: Jonas Liljegren <jonas@rit.se>
Date: 20 Nov 2000 16:59:44 +0100
To: "McBride, Brian" <bwm@hplb.hpl.hp.com>
Cc: Dan Brickley <danbri@w3.org>, Seth Russell <seth@robustai.net>, RDF-IG <www-rdf-interest@w3.org>
Message-ID: <87bsvamy6n.fsf@jonas.rit.se>
"McBride, Brian" <bwm@hplb.hpl.hp.com> writes:

> [snip]
> > Here is the example from M&S:
> > 
> >   <rdf:RDF
> >     xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
> >     xmlns:a="http://description.org/schema/">
> >     <rdf:Description>
> >       <rdf:subject resource="http://www.w3.org/Home/Lassila" />
> >       <rdf:predicate 
> > resource="http://description.org/schema/Creator" />
> >       <rdf:object>Ora Lassila</rdf:object>
> >       <rdf:type 
> > resource="http://www.w3.org/1999/02/22-rdf-syntax-ns#Statement" />
> >       <a:attributedTo>Ralph Swick</a:attributedTo>
> >     </rdf:Description>
> >   </rdf:RDF>
> > 
> > The example uses the property a:attributedTo.  You can't attribute an
> > abstract statement to one person.  The example view the reified
> > statement as a stating.
> I disagree.  I may assert the statement S1.  You may assert it. Dan may
> assert it.  This can be modelled just fine by adding a:attributedTo
> properties as in the example you give above, quoting from M&S.
> > 
> > The reasoning for this is the same as before.  Let me repeat the
> > example using This example.
> No!  The claim was that the examples in M&S have a problem.  If that is
> true, that could be good reason for changing M&S.  But the example you
> use to point out a problem is not in M&S.  The examples in M&S work just
> fine. 

The M&S example is not directly faulty.  But it doesn't use the
#stating construction, suggested for the problem I have described.

If we, as you suggest, view the reified statements as representing the
statement rather than the stating, we would have to invent a property
to represent statings in the cases there we want to say more than one
thing about the statement.

It would be unclean to mix #stating properties with properties like
the a:attributedTo in the example.

It seems more practical to view the reified statement as a stating.
Either that, or extend the M&S to include the stating property.

> The case to be met is that a statement is a triple (s,p,o) which
> is uniquely defined by its three components.  The exert I just
> quoted from M&S 4.1 says that a reified statement models a 
> statement.  Not the stating of a statement.  Current M&S
> implies therefore that a reified statement is uniquely determined
> by its subject, predicate and object.

Yes.  But it doesn't discuss how to handle the problem discussed.

Your interpretation is logically correct.  But we can change it.  My
vote is to change it.

I would like Dan Brickley to make an official ruling, and update [1],
and later clarify the issue in a revision of the M&S document.

/ Jonas Liljegren

The Wraf project http://www.uxn.nu/wraf/
Sponsored by http://www.rit.se/
Received on Monday, 20 November 2000 11:07:20 UTC

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