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erratum ... RE: allValuesFrom and rdfs:domain

From: Bernard Vatant <bernard.vatant@mondeca.com>
Date: Thu, 18 Dec 2003 10:59:41 +0100
To: "Bernard Vatant" <bernard.vatant@mondeca.com>, "Www-Rdf-Logic@W3. Org" <www-rdf-logic@w3.org>
Message-ID: <GOEIKOOAMJONEFCANOKCCEAMCOAA.bernard.vatant@mondeca.com>


Oops ... Please read below

<owl:Class rdf:ID="InvisibleThing">
  <owl:complementOf>
    <owl:Class rdf:about="#VisibleThing"/>
  </owl:complementOf>
</owl:Class>

instead of

<owl:Class rdf:ID="InvisibleThing">
  <owl:complementOf>
    <owl:Class rdf:about="#VisibleObject"/>
  </owl:complementOf>
</owl:Class>

Thanks

Bernard Vatant
Senior Consultant
Knowledge Engineering
Mondeca - www.mondeca.com
bernard.vatant@mondeca.com


> -----Message d'origine-----
> De : www-rdf-logic-request@w3.org
> [mailto:www-rdf-logic-request@w3.org]De la part de Bernard Vatant
> Envoye : jeudi 18 decembre 2003 10:38
> A : Www-Rdf-Logic@W3. Org
> Objet : owl:allValuesFrom and rdfs:domain
>
>
>
>
> I need some help from experts in logic ...
>
> I've sent a few days ago a message about "TexasThings" example
> in OWL Guide
> (see below), where the interpretation of allValuesFrom seems wrong to me.
> Without answer so far from there, I push the question here.
>
> Suppose I have the following - more enlightening to me at least
> than Texas
> Things :))
>
> <owl:Class rdf:ID="BlueThing">
>   <owl:equivalentClass>
>     <owl:Restriction>
>       <owl:onProperty rdf:resource="#color" />
>       <owl:allValuesFrom rdf:resource="#ShadeOfBlue" />
>     </owl:Restriction>
>   </owl:equivalentClass>
> </owl:Class>
>
> <owl:ObjectProperty rdf:ID="color">
>   <rdfs:domain rdf:resource="#VisibleThing"/>
> </owl:ObjectProperty>
>
> What can be asserted between the classes BlueThing and VisibleThing ?
>
> Of course, if some BlueThing X has a value for "#color", then X is in the
> domain of "#color". But using "allValuesFrom" means that some other
> BlueThing Y may not have any value at all for this property.
> How can this happen? Quite naturally, if Y is not a VisibleThing
> one might
> not be able to specify any value for its color. One knows somehow Y is a
> BlueThing, without being able to specify any ShadeOfBlue.
>
> So a BlueThing is not necessarily a VisibleThing.
>
> There is more tricky.
>
> <owl:Class rdf:ID="InvisibleThing">
>   <owl:complementOf>
>     <owl:Class rdf:about="#VisibleObject"/>
>   </owl:complementOf>
> </owl:Class>
>
> Does the following triple hold?
>
> InvisibleThing  rdfs:subClassOf  BlueThing
>
> Sounds weird ... but I can't find any solid argument against it.
>
> Bernard
>
> Bernard Vatant
> Senior Consultant
> Knowledge Engineering
> Mondeca - www.mondeca.com
> bernard.vatant@mondeca.com
>
>
> -----Message d'origine-----
> Envoye : lundi 15 decembre 2003 19:21
> A : public-webont-comments@w3.org
> Objet : TexasThings and owl:equivalentClass
>
> Seems to me that there is something wrong, or at least
> misleading with the
> example of "TexasThings"
> http://www.w3.org/TR/owl-guide/#equivalentClass1
>
> <owl:Class rdf:ID="TexasThings">
>   <owl:equivalentClass>
>     <owl:Restriction>
>       <owl:onProperty rdf:resource="#locatedIn" />
>       <owl:allValuesFrom rdf:resource="#TexasRegion" />
>     </owl:Restriction>
>   </owl:equivalentClass>
> </owl:Class>
>
> First it would certainly be better to have the singular
> "TexasThing" rather
> than plural "TexasThings" :)
>
> "TexasThings are exactly those things located in the Texas region ..."
>
> This is obviously wrong. There is an allValuesFrom, but not a
> someValuesFrom here. As defined, it means : If TexasThings are located
> somewhere, they are located in Texas region.
>
> An further on
>
> " ... The difference between using owl:equivalentClass here and using
> rdfs:subClassOf is the difference between a necessary condition and a
> necessary and sufficient condition. With subClassOf, things that are
> located in Texas are not necessarily TexasThings. But, using
> owl:equivalentClass, if something is located in Texas, then it must be in
> the class of TexasThings."
>
> ... but not the other way round, unfortunately.
>
> In fact under this definition any thing located nowhere is a Texas Thing.
> Thinking about it, maybe it makes sense after all. Nowhere is indeed in
> Texas, and especially its middle ... :))
>
>
>
Received on Thursday, 18 December 2003 05:00:01 GMT

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