Re: OWL and RDFS (from public-webont-comments@w3.org)

From: "Davide Noaro" <noarodavide@libero.it>
Subject: OWL and RDFS (from public-webont-comments@w3.org)
Date: Sun, 6 Apr 2003 16:02:53 +0200

> Message-ID: <001301c2f9c8$08be7470$221f0125@shadow>
> From: "Davide Noaro" <noarodavide@libero.it>
> To: <public-webont-comments@w3.org>
> Date: Thu, 3 Apr 2003 12:01:45 +0200
> Subject: Re: [closed] Re: OWL Questions!
> 
> Thank you very much for your answers,
> but i don't understand well.....
> 
> you say:
> 
> >1 - OWL is an extension of RDF(S) -- that is, all RDF and RDFS 
> >documents are legal OWL Full documents  
> 
> OK!! If OWL is an extension....
> 
> >and all OWL documents are 
> >legal RDFS documents
> 
> HOW is it possible if OWL allow more expressivity than RDFS?? 

OWL is a semantic extension of RDFS.

For example, if you say
	<owl:Class rdf:ID="c">
	  <owl:equivalentTo>
	    <owl:Restriction>
	     <owl:onProperty rdf:about="#r" />
	     <owl:toClass rdf:about="#d" />
	    </owl:Restriction>
	  </owl:equivalentTo>
	</owl:Class">
Then you are writing in the syntax for RDF, and there is an RDF meaning for
what you wrote.  However, you could also treat the above as OWL, and you
would get more meaning for the above in OWL.

> So OWL and RDFS are equivalent .... 
> 
> and after you say:
> 
> >Not all RDFS documents are necesssarily in OWL Lite or OWL 
> >[DL]. 
> 
> So not ALL RDFS documents are OWL documents i understand....

Not all RDFS documents are OWL Lite or OWL DL documents, but all RDFS
documents are OWL Full documents.

> Have you make a mistake in writing or is all true what have you said? 

There was a typo.

> ************************************************************************************
> Here what i have understand:
> 
> - OWL is an extension of RDFS and allow more expressivity than RDFS, in
> fact you can, for example say that a property is required
> (owl:minCardinality of 1) or optional  (owl:minCardinality of 0) and
> other such things than IN RDFS YOU CAN'T! 

Well, when you say these things you get more meaning from them.

> -SO RDFS document are valid OWL documents, but NOT ALL OWL documents ARE
> VALID RDFS DOCUMENTS. ( e.g. owl document in which i use
> owl:minCardinality, that in rdfs doesn't exist ) 

No.  Such documents are RDF(S) documents.  There is nothing in RDFS that
prevents you from using owl:minCardinality, for example.  It is just that
you don't get the OWL meaning unless you are treating it as an OWL
document.

> ********************************************************************************************
> 
> Thanks if you can clarify me again the situation.
> Davide.

Peter F. Patel-Schneider
Bell Labs Research
Lucent Technologies

Received on Tuesday, 8 April 2003 13:18:50 UTC