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Re: ISSUE: Classes as instances

From: Guus Schreiber <schreiber@swi.psy.uva.nl>
Date: Thu, 18 Jul 2002 17:44:09 +0200
Message-ID: <3D36E249.1030003@swi.psy.uva.nl>
To: Ian Horrocks <horrocks@cs.man.ac.uk>
CC: Raphael Volz <volz@aifb.uni-karlsruhe.de>, Webont <www-webont-wg@w3.org>

Ian Horrocks wrote:
> On July 11, Raphael Volz writes:
> 
>>TITLE: Classes as instances
>>DESCRIPTION:
>>In certain cases it is necessary to represent "classes as instances"
>><p>
>><b>Scenario 1:</b>
>>Representing thesauri in OWL.
>>Thesauri are build on terms and have a set of predefined relations
>>to establish links between terms. One can distinguish two kinds
>>of approaches to represent thesauri for RDF(S):
>><ol>
>><li>Syntactic representation, such as done in
>>http://www.semanticweb.org/library/,
>>does not use classes to represent terms (or synsets in WordNet).
>>OWL could be
>>used to represent all terms as instances of a class <i>Term</i>.
>>Additionally
>>the set of relations can be tranlated to properties having this class as
>>domain
>>and range. Eventually additional features of these properties, such as
>>transitivity may
>>be specified, e.g. for the hyperonym relation.
>><li>&quot;Semantic representation&quot;. Such as work carried out at the
>>university
>>of Karlsruhe. Here terms are converted to OWL classes and the hyperonym
>>relation is converted
>>to subclassof properties. All other thesaurus properties are difficult to
>>translate since
>>they are used to relate classes. However, in OWL properties do only relate
>>instances which are members of
>>the classes specified in domain and range constraints. The semantically
>>correct representation would
>>be to extend the metamodel of the ontology language, leading to information
>>that cannot be processed
>>by OWL aware agents. <p>
>>Another possibility is to treat classes as instances allowing to related
>>classes using properties
>>other than subclassof.
> 
> 
> This was covered by Peter's reply to Guus - you can get what you want
> simply by declaring the hyponym relation to be transitive. Converting
> hyponym to (a subProperty of) subClass seems to be a hack that is
> being used in order to get the behaviour you want from RDFS.
> 

As I said in my reply to Peter: transitive does not convey what you 
want. Seeing hyponym as a sort of subclass relation is not unreasonable 
and certainly not a hack (go and tell that at a WordNet conference).

Guus


[..]

-- 
A. Th. Schreiber, SWI, University of Amsterdam,
Home page: http://www.swi.psy.uva.nl/usr/Schreiber/home.html
Received on Thursday, 18 July 2002 11:38:15 GMT

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