RE: owl:Class and owl:Thing

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> 

<!--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>

>>>>>>>>>>>>>>>>>>>

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.

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

Regards,
Hans

[1] http://wonderweb.semanticweb.org/deliverables/documents/D1.pdf

=========================================================================

-----Original Message-----
From: Dave Reynolds [mailto:der@hplb.hpl.hp.com] 
Sent: Thursday, March 30, 2006 23:58
To: Hans Teijgeler
Cc: SW-forum
Subject: Re: owl:Class and owl:Thing

Hans Teijgeler wrote:

> In OWL-Full it is possible to have a class that also is an individual 
> in the context of a class-of-class. We have that a lot. Now my 
> question is whether or not I shall call the same object an owl:Class 
> when it is in the role of class, and call it an owl:Thing when it is 
> in the role of individual. If not, what shall prevail? Or must I declare
it twice?

You don't *need* to declare it at all in OWL/full.

If you use a resource in the role of a class then it can be inferred to be a
class. For example, if you use it as the object of an rdf:type statement or
in an rdfs:subClassOf statement then it can be inferred to be an rdfs:Class.
In OWL/full rdfs:Class and owl:Class have the same extension.

Similarly it can be inferred to be an owl:Thing (for trivial reasons in
OWL/full) and probably some subclass of owl:Thing based on the domain/range
of whatever properties you apply to it.

However, it may be useful for human readers of your ontology if you document
it's dual nature by declaring both it's types explicitly along with
appropriate rdfs:comments.

Dave

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Received on Friday, 31 March 2006 07:28:14 UTC