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RE: Proposed response for timbl-02 (reification semantics)

From: Jan Grant <Jan.Grant@bristol.ac.uk>
Date: Thu, 10 Apr 2003 11:51:03 +0100 (BST)
To: "Patrick.Stickler" <Patrick.Stickler@nokia.com>
cc: danbri <danbri@w3.org>, bwm <bwm@hplb.hpl.hp.com>, gk <gk@ninebynine.org>, w3c-rdfcore-wg <w3c-rdfcore-wg@w3.org>
Message-ID: <Pine.GSO.4.44.0304101141390.14291-100000@mail.ilrt.bris.ac.uk>

On Thu, 10 Apr 2003, Patrick.Stickler wrote:

> > -----Original Message-----
> > From: ext Dan Brickley [mailto:danbri@w3.org]

> > here's a sketch towards testcase, sorry haven't polished this up but
> > the intent should hopefully be clear. It takes your sample and
> > shows the kinds of interferences that OWL-happy systems might make in
> > the face of knowing some things have multiple URIs and OWLs ability to
> > express equality, directly (sameFooAs) or indirectly
> > (InverseFunctionalProperty).
> >
> > [[
> >   _:s rdf:type rdf:Statement ;
> >    _:s rdf:subject <s1> ;
> >    _:s rdf:predicate <p1> ;
> >    _:s rdf:object <o1> ;
> >    _:s #source <http://some.server/some_schema.rdf>
> >
> > <s1> owl:sameIndividualAs <s2>
> > <p1> owl:sameIndividualAs <p2>
> > <o1> owl:sameIndividualAs <o2>
> >
> > ...which with OWL semantics I believe gets us to:
> >
> >    _:s rdf:type rdf:Statement ;
> >    _:s rdf:subject <s2> ;
> >    _:s rdf:subject <s1> ;
> >    _:s rdf:predicate <p2> ;
> >    _:s rdf:predicate <p1> ;
> >    _:s rdf:object <o2> ;
> >    _:s rdf:object <o1> ;
> >    _:s #source <http://some.server/some_schema.rdf>
> >
> >
> > which includes the subset of triples,
> >
> >    _:s rdf:type rdf:Statement ;
> >    _:s rdf:subject <s2> ;
> >    _:s rdf:predicate <p2> ;
> >    _:s rdf:object <o2> ;
> >    _:s #source <http://some.server/some_schema.rdf>
> >
> > which strongly suggests that the triple
> >
> >    <s2> <p2> <o2> .
> >
> > ...can be found in some_schema.rdf, rather than 'can be
> > deduced from...'.
> > ]]

If you want to distinguish between symbols rather than the things they
refer to, wouldn't you also balk at

	<s1> owl:sameIndividualAs <s2>

since they're clearly not the same? Should we ask that a health warning
be attached to owl:sameIndividualAs?

I'm really concerned about this test case. It seems to mix formal
notions (owl:sameIndividualAs) and woolly ones ("strongly suggests").

Presumably there is an analogous warning to be attached to datatypes?
Since (sooner or later) we might find the situation that

	_:jan eg:age "21.0"^^xsd:decimal .

"strongly implies" that

	_:jan eg:age "21"^^xsd:int .


We decided NOT to deprecate reification, but to attach a note indicating
that people (trying to) use it for quotation were getting it wrong.
Adding more and more "health warning" (this might go wrong, this
strongly suggests something bad, it makes your nose fall off, etc) seems
like de facto deprecation to me.

As we already saw when DanC and I discussed options for "alternatives"
to reification, there are hard decisions to be made when it comes to
designing a quotation mechanism. The WG didn't explore those options;
currently, if you are interested in the URIs people used to express some
RDF, you are stuck with slapping the document in a parseType="Literal"
:-/




-- 
jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/
Tel +44(0)117 9287088 Fax +44 (0)117 9287112 http://ioctl.org/jan/
Just because I have nothing to hide doesn't mean I have nothing to fear.
Received on Thursday, 10 April 2003 06:52:22 EDT

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