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RE: rdfs:resource

From: Pedro Assis in Oporto <passis@dee.isep.ipp.pt>
Date: Fri, 25 Jul 2003 15:45:41 +0100 (WEST)
To: Jon Hanna <jon@spin.ie>
cc: www-rdf-interest@w3.org
Message-ID: <Pine.LNX.4.44.0307251321230.31637-100000@douro.dee.isep.ipp.pt>

Hi Hanna,

On Fri, 25 Jul 2003, Jon Hanna wrote:

> <cims:qualifierFlavor> <rdf:type> <cims:NamedElement> . says that
> <cims:qualifierFlavor> is a NamedElement, and as such anything that is true
> of all NamedElements is true of qualifierFlavor, qualifierFlavor can be used
> where any NamedElement could be used, and so on. This is I think the
> relationship you want between <cims:qualifierFlavor> and
> <cims:NamedElement>.

Correct. 

> 
> <cims:qualifierFlavor> <rdfs:subProperty> <cims:NamedElement> .
> Entails that both <cims:qualifierFlavor> and <cims:NamedElement> are
> properties, and as such it is possible to say <A> <cims:NamedElement> <B>.

Yes, and that is a problem. In my view this is wrong as the NamedElement
is "conceptual" or restriction (if you prefer), i.e. it states that all
CIM elements must be named.

> 
> It's worth noting that while <rdfs:Class> <rdfs:subClassOf> <rdfs:Resource>
> .
> <rdfs:Resource> <rdf:type> <rdfs:Class> .
> 
> That is, Class is a subClass of Resource, but Resource is a type of Class.
> 
> It is the difference between these two types of relationship that are coming
> into play here.
> 
> Taking a less abstract concept than "NamedElement" Cod is a sub-class of
> Fish, and hence anything that is a Cod is also a Fish, so we have a
> subClassOf relationship. It does not follow however that the concept of
> "Cod" is a itself a fish, and indeed it isn't.

Yes, I understand the subtlety of that argument: one thing is the 
description of the class members (their characteristics) and another is 
the class as an individual (a concept, a thing).

> You began your original mail with:
> 
> "Assuming,
> 
> cims:NamedElement rdf:type rdfs:Resource
> cims:qualifierFlavor rdf:type rdf:Property
> cims:Schema rdf:type rdfs:Class"

Yes, this is (was) my original idea, but now I think that some of the 
original concepts/restrictions are not adequate to be described by 
RDF/RDFS (even with OWL/DAML+OIL I'm not sure...)

> It might be worth considering whether the fact that all objects in your
> "native" ontology are instances of NamedElement is something that is still
> of value when expressed in RDF. I couldn't say without seriously examining
> how the entire ontology works, and you may have already considered and
> dismissed the idea, but it might be worth thinking about.
>

Yes, the work that I've done so far eventually points in that direction -
some of the initial concepts/restrictions are just not adequate to be
described in RDF. I'll make a revision of my work and submit it to the
list.

Thanks for the time you take in answering my questions.

Regards,

-- 
Pedro

passis@dee.isep.ipp.pt | Tel. +351 22 8340500 Ext. 1712
Received on Friday, 25 July 2003 10:45:53 GMT

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