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

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Thu, 10 Apr 2003 14:25:16 +0200
To: "Dan Brickley" <danbri@w3.org>, <Patrick.Stickler@nokia.com>
Cc: <Jan.Grant@bristol.ac.uk>, <bwm@hplb.hpl.hp.com>, <gk@ninebynine.org>, <w3c-rdfcore-wg@w3.org>
Message-ID: <BHEGLCKMOHGLGNOKPGHDEEHJCBAA.jjc@hpl.hp.com>


Putting OWL test case editor's hat on.

OWL Test Cases WD has recently been published.
I would quite like at least one comment, while the other drafts get the
glory!

Maybe RDF Core WG would like to submit an OWL Test Case with a formal
request to have it included in the OWL Test Cases.

Jeremy


> -----Original Message-----
> From: w3c-rdfcore-wg-request@w3.org
> [mailto:w3c-rdfcore-wg-request@w3.org]On Behalf Of Dan Brickley
> Sent: 10 April 2003 13:34
> To: Patrick.Stickler@nokia.com
> Cc: Jan.Grant@bristol.ac.uk; bwm@hplb.hpl.hp.com; gk@ninebynine.org;
> w3c-rdfcore-wg@w3.org
> Subject: Re: Proposed response for timbl-02 (reification semantics)
>
>
>
> * Patrick.Stickler@nokia.com <Patrick.Stickler@nokia.com>
> [2003-04-10 14:06+0300]
> >
> >
> > > -----Original Message-----
> > > From: ext Jan Grant [mailto:Jan.Grant@bristol.ac.uk]
> > > Sent: 10 April, 2003 13:51
> > > To: Stickler Patrick (NMP/Tampere)
> > > Cc: danbri; bwm; gk; w3c-rdfcore-wg
> > > Subject: RE: Proposed response for timbl-02 (reification semantics)
> > >
> > >
> > > 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?
> >
> > I have no problem with <s1> and <s2> denoting the same thing.
>
> me neither, though I agree it can seem an odd way to express things.
> OWL, for better or worse, does give us a way to write RDF/XML instance
> data that (when read wearing OWL glasses) tells us that two URIs denote
> the same thing. That's just the world RDF lives in now, and the world
> reification will be deployed in.
> >
> > > Should we ask that a
> > > health warning
> > > be attached to owl:sameIndividualAs?
> >
> > Not at all.
> >
> > > 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
>
> yes (jang), my 'strongly implies' was a bit vague. At that point I
> only had Patrick's property name ('source') to go on. Since then we have
> seen the schema, comments on which below.
>
> > >
> > > 	_:jan eg:age "21"^^xsd:int .
> >
> > After thinking about this some more, I've realized that I don't have
> > a problem with the inference you suggested. I.e., I'm OK with
> > the following entailment
> >
> > {
> >    _:s a rdf:Statement .
> >    _:s rdf:subject <s1> .
> >    _:s rdf:predicate <p1> .
> >    _:s rdf:object <o1> .
> >    _:s #source #x .
> >    <s1> owl:sameIndividual <s2> .
> >    <p1> owl:sameIndividual <p2> .
> >    <o1> owl:sameIndividual <o2> .
> > }
> > log:implies
> > {
> >    _:s a rdf:Statement .
> >    _:s rdf:subject <s2> .
> >    _:s rdf:predicate <p2> .
> >    _:s rdf:object <o2> .
> >    _:s #source #x .
> > }
> >
> > because reification, as now defined, is not quoting.
>
> Ah, ok, that makes things simpler. My previous mail was written
> in concern that
> you somehow wanted to block this inference from going through.
>
> > If we add verbage of any kind, then it should be to the effect
> > that such entailments hold.
>
> OK. Patrick, hope you don't mind us picking on you as a sample user of
> rdf reification, but let's follow this one through a bit further.
>
> Your current defintion for 'source' is as follows:
>
>       <rdfs:Property rdf:about="&rdfx;/source">
>          <rdfs:comment>An RDF schema in which the statement
> occurs.</rdfs:comment>
>          <rdfs:domain rdf:resource="&rdf;#Statement"/>
>          <rdfs:range rdf:resource="&rdfx;/Schema"/>
>       </rdfs:Property>
>
> This (sorry jang)
> 'strongly suggests'
> 'seems to me to be saying'
> 'leads me as an implementor to believe'
>
> that because of
>
> >    _:s a rdf:Statement .
> >    _:s rdf:subject <s2> .
> >    _:s rdf:predicate <p2> .
> >    _:s rdf:object <o2> .
> >    _:s #source #x .
>
> the RDF statement
>
> <s2> <p2> <o2> .
>
> ...occurs in the RDF schema referenced.
>
> Now you don't formally define 'occurs' here.
> For the sake of our example scenario, let us assume that <s2>, <p2> and
> <o2> URIrefs are not anywhere to be found in the RDF document that
> the 'source' property references.
>
> The work of our health warning is to help RDF vocabulary creators use
> language in their defintions for properties such as this which won't
> raise inaccurate expectations. In this case, an inaccurate expedtation
> would be that the URIs <s2>, <p2> and <o2> are labels on a triple
> from the graph serialized in the RDF schema document referenced by the
> source property. (or some refinement of that; it's hard to word
> this stuff)
>
> Does that seem correct? ie. that words like 'occurs' in this context
> are super-slippery...
>
> Dan
>
>
Received on Thursday, 10 April 2003 08:25:51 EDT

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