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Re: TEST: Functional and InverseFunctional tests for approval

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 05 Sep 2002 09:29:05 -0400 (EDT)
Message-Id: <20020905.092905.93687464.pfps@research.bell-labs.com>
To: jos.deroo.jd@belgium.agfa.com
Cc: www-webont-wg@w3.org

From: "Jos De_Roo" <jos.deroo.jd@belgium.agfa.com>
Subject: Re: TEST: Functional and InverseFunctional tests for approval
Date: Thu, 5 Sep 2002 15:06:35 +0200

[...]

> What I forgot to mention was also the point we discussed in
> http://lists.w3.org/Archives/Public/www-webont-wg/2002Aug/0203.html
> 
> [[[
> OK, e.g. we can't have existentials in the conclusion that are
> in the domain of an owl:InverseFunctionalProperty because that
> property is simply not defined over it's whole range
> (lists in the range of e.g. owl:intersectionOf could contain a
> mix of resources being classes, properties, classes/properties
> and so many of such intersections simply don't exist and in
> general we can't give the list constraints in the premis)
> ]]]

This doesn't have anything to do with concluding that an inverse functional
property implies atmost one on its inverse.  For example, one could have a
test like

DESCRIPTION:

If prop belongs to owl:InverseFunctionalProperty
then any OWL object has at most one value for its inverse prop.

RATIONALE:

This tests an inference that is not dependant upon the previous approved
tests for owl:InverseFunctionalProperty.

PREMISE

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
	 xmlns:owl ="http://www.w3.org/2002/07/owl#">
    <owl:ObjectProperty rdf:about="http://www.example.org/foo#porp">
     <owl:inverseOf>
      <owl:InverseFunctionalProperty rdf:about="http://www.example.org/foo#prop" />
     </owl:inverseOf>
    </owl:ObjectProperty>
    <owl:Thing rdf:about="http://www.example.org/foo#object" />
</rdf:RDF>

CONCLUSION

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
	 xmlns:owl ="http://www.w3.org/2002/07/owl#">
    <owl:Thing rdf:about="http://www.example.org/foo#object">
      <rdf:type>
        <owl:Restriction>
	  <owl:onProperty>
	    <owl:ObjectProperty rdf:about="http://www.example.org/foo#porp" />
	  </owl:onProperty>
	  <owl:maxCardinality>1</owl:maxCardinality>
        </owl:Restriction>
      </rdf:type>
    </owl:Thing>
</rdf:RDF>

Note:  I'm not advocating this as one of the OWL approved tests!  I believe
       that it bundles up too many things together.  I would prefer a test
       whose conclusion is that porp is a FunctionalProperty.

> and also DanC's & JeremyC's arguments of course

Yes, there are some in the working group that have advocated positions that
are counter to these tests.  However, it is up to them to oppose the test,
if they so desire.  The fact that someone else *might* oppose a test is not
an argument against the test.  My view is that if one wants to oppose a
test then one has to do so directly.

> Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/

peter
Received on Thursday, 5 September 2002 09:29:24 GMT

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