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Re: Question about skos:concept

From: Jyotishman Pathak <jyotishman.mayo@gmail.com>
Date: Mon, 3 Aug 2009 12:50:16 -0500
Message-ID: <897e9e390908031050w7ec93756pe8eb28514c58b208@mail.gmail.com>
To: Thomas Bandholtz <thomas.bandholtz@innoq.com>
Cc: Antoine Isaac <aisaac@few.vu.nl>, public-esw-thes@w3.org
Thomas,

My understanding is that the last bit of information in your email does not
hold:

rdfs:Resource
    rdfs:Class
       owl:Class
          skos:Concept

skos:Concept is rdf:type owl:Class (not subClassOf). So, I think the
subClassOf hierarchy that you pointed out isn't holding...unless I am
terribly missing something here.

- Jyoti

On Mon, Aug 3, 2009 at 12:44 PM, Thomas Bandholtz <
thomas.bandholtz@innoq.com> wrote:

> Hi Antoine & Jyoti,
>
> isn't it much more simple?
>
> in OWL, "owl:Class is defined as a subclass of rdfs:Class" [1].
>
> <rdfs:Class rdf:ID="Class">
>  <rdfs:label>Class</rdfs:label>
>  <rdfs:subClassOf rdf:resource="&rdfs;Class"/>
> </rdfs:Class>
>
> In RDFS you can read:
>
> "2.1 rdfs:Resource All things described by RDF are called resources, and
> are instances of the class rdfs:Resource. This is the class of
> everything. All other classes are subclasses of this class.
> 2.2 rdfs:Class This is the class of resources that are RDF classes." [2]
>
> <rdfs:Class rdf:about="http://www.w3.org/2000/01/rdf-schema#Class">
>  <rdfs:isDefinedBy rdf:resource="http://www.w3.org/2000/01/rdf-schema#"/>
>  <rdfs:label>Class</rdfs:label>
>  <rdfs:comment>The class of classes.</rdfs:comment>
>  <rdfs:subClassOf rdf:resource="
> http://www.w3.org/2000/01/rdf-schema#Resource"/>
> </rdfs:Class>
>
> That's why skos:Concept does not need a subClassOf rdfs:Resource, it is
> inherited.
> Class hierarchy is:
>
> rdfs:Resource
>    rdfs:Class
>       owl:Class
>          skos:Concept
>
> Hope this helps,
>
> Thomas
>
> [1] http://www.w3.org/TR/owl-ref/#Class
> [2] http://www.w3.org/TR/rdf-schema/#ch_resource
>
>
> Antoine Isaac schrieb:
> > Hi Jyoti,
> >
> > Indeed there is no explicit subClassOf relationship between
> > skos:Concept and rdfs:Resource.
> >
> > But it is implicitly here: if I'm not mistaken, an RDFS/OWL inference
> > engine can get it from the RDFS and OWL semantics, especially using
> > [1] which has the following axiom:
> > If x is in IC then <x, I(rdfs:Resource)> is in IEXT(I(rdfs:subClassOf))
> > ( where IC = ICEXT(I(rdfs:Class)) )
> >
> > Cheers,
> >
> > Antoine
> >
> > [1] http://www.w3.org/TR/rdf-mt/#vocabulary_entail
> >
> >
> >
> >> Hello all,
> >>
> >> I am seeking a clarification about skos:concept.
> >>
> >> <rdf:Description rdf:about="#Concept">
> >> <rdfs:label xml:lang="en">Concept</rdfs:label>
> >> <rdfs:isDefinedBy rdf:resource="http://www.w3.org/2004/02/skos/core"/>
> >> <skos:definition xml:lang="en">An idea or notion; a unit of
> >> thought.</skos:definition>
> >> <!-- S1 -->
> >> <rdf:type rdf:resource="http://www.w3.org/2002/07/owl#Class"/>
> >> </rdf:Description>
> >>
> >> 1.) At present, skos:concept is defined as an instance of owl:class
> >> (and hence, an instance of rdfs:resource). However, I do not see any
> >> "explicit" subClassOf relationship between skos:concept and
> >> rdfs:resource. Am I correct in assuming that such a relationship does
> >> not exist?
> >>
> >> 2.) If the answer to question# 1 is yes, could you please explain
> >> (preferably with an example) why such an assertion was not included
> >> in the specification?
> >>
> >> Thank you in advance for your replies!
> >>
> >> Cheers,
> >> - Jyoti
> >
> >
> >
>
>
> --
> Thomas Bandholtz, thomas.bandholtz@innoq.com, http://www.innoq.com
> innoQ Deutschland GmbH, Halskestr. 17, D-40880 Ratingen, Germany
> Phone: +49 228 9288490 Mobile: +49 178 4049387 Fax: +49 228 9288491
>
>
Received on Monday, 3 August 2009 17:51:14 UTC

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