Re: Question about skos:concept

Hi,

I won't check everything in Thomas' mail, but one thing is sure: the following sentence gives the answer to Jyoti's question.

> 2.1 rdfs:Resource [...] All other classes are subclasses of this class.

And I'm sorry for the shortness of my previous mail (as Simon, I was in a hurry...). But I assure you that it gave exactly the same axiom, in the formal way:
- "x is in IC" stands for "x is a class"
- "<x, I(rdfs:Resource)> is in IEXT(I(rdfs:subClassOf))" stands for "x is a subclass of rdfs:Resource".

Note that Simon's comment addresses a different matter, namely "everything is an instance of rdfs:Resource", as opposed to "every class is a subclass of rdfs:Resource".
But Simon is in fact also right, especially for the classes: any class is also an instance of rdfs:Resource. 
This is what is meant by the part "Resource. All things described by RDF are called resources, and are instances of the class rdfs:Resource." that Thomas quoted.
But this time, I will spare you the formal description ;-)

Cheers,

Antoine


> Jyoti,
> 
> oops I was wrong - of course you are right.
> Probably Antoine has given the better answer.
> 
> Anyway, why are you looking for a subClassOf relationship between
> skos:Concept and rdfs:Resource?
> For what do you need it?
> I can hardly imagine a use case.
> 
> Thomas
> 
> Jyotishman Pathak schrieb:
>> 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 <mailto: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
>>     <mailto: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 21:54:15 UTC