W3C home > Mailing lists > Public > semantic-web@w3.org > March 2006

Re: owl:Class and owl:Thing

From: Dave Reynolds <der@hplb.hpl.hp.com>
Date: Fri, 31 Mar 2006 14:02:36 +0100
Message-ID: <442D286C.6030102@hplb.hpl.hp.com>
To: Hans Teijgeler <hans.teijgeler@quicknet.nl>
CC: "'SW-forum'" <semantic-web@w3.org>

Hans Teijgeler wrote:

> Hi Dave,
> 
> Thanks for your response!
> 
> Just to make certain that I understood you well, please confirm that this
> code is correct:
> 
> 
> 
> In a triple store for a data model with base URI
> xml:base="http://www.15926.org/dm/2006-02" we find:
> 
>     <owl:Class rdf:ID="ClassOfInanimatePhysicalObject"> 
>         <rdfs:subClassOf rdf:resource="#ClassOfArrangedIndividual"/> 
>     </owl:Class>
> 
> In a triple store for a vocabulary for core classes with base URI
> xml:base="http://www.15926.org/rd/2006-02" we find:
> 
> <!--the core class 'Pump'-->
>     <owl:Class rdf:ID="Pump"> 
>         <rdf:type
> rdf:resource="http://www.15926.org/dm/2006-02#ClassOfInanimatePhysicalObject
> "/> 
>     </owl:Class> 

[That is legal OWL/full and does what you say you want. It doesn't explain 
why you are modelling InanimatePhysicalObject as a meta-class instead of as 
simply being a class of which Pump is a subclass but I'm sure you have good 
reasons.]

> <!--the core class 'CentrifugalPump'-->
>     <owl:Class rdf:ID="CentrifugalPump"> 
>         <rdfs:subClassOf rdf:resource="#Pump"/> 
>     </owl:Class> 
> 
> In a triple store of a pump supplier with base URI
> xml:base="http://www.abc-corp.com/sys4502" we find:
> 
> <!--a pump class in his catalog-->
>     <owl:Class rdf:ID="Model-AK150-CentrifugalPump"> 
>         <rdfs:subClassOf
> rdf:resource="http://www.15926.org/rd/2006-02#CentrifugalPump"/> 
>     </owl:Class> 
> 
> <!--a particular pump manufactured by him-->
>     <owl:Thing rdf:ID="PHO-347621">
>         <rdfs:label>pump with serial number AK-83492</rdfs:label>
>         <rdf:type rdf:resource="#Model-AK150-CentrifugalPump"/>
>     </owl:Thing>

Fine, though the owl:Thing bit is redundant. This might be easier to read as:
    <ns:Model-AK150-CentrifugalPump rdf:ID="PHO-347621">
       <rdfs:label>pump with serial number AK-83492</rdfs:label>
    </ns:Model-AK150-CentrifugalPump>

but there is no semantic differnce between this and your version.

> The class Pump is such a case where it is both an owl:Class and an
> individual, as a member of the class ClassOfInanimatePhysicalObject. Yet it
> has not been declared as owl:Thing. I understand from you that that is OK.

Yes.

> Is it possible that owl:Individual, that once existed [1], was meant to be
> the class of REAL individuals in a REAL world?

I don't think so, perhaps before OWL went to Rec there was a different 
mapping from OWL abstract syntax to RDF. Someone from webont would have to 
comment on that.

Dave
Received on Friday, 31 March 2006 13:03:09 UTC

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