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Re: Why isn't FunctionalProperty a subClassOf owl:ObjectProperty?

From: Qu Yuzhong <yzqu@seu.edu.cn>
Date: Wed, 5 Mar 2003 09:49:02 +0800
Message-ID: <00bb01c2e2b9$66b8a800$1e0f77ca@proxy.seu.edu.cn>
To: "Roger L. Costello" <costello@mitre.org>
Cc: "Bob MacGregor" <macgregor@ISI.EDU>, "Peter Crowther" <Peter.Crowther@networkinference.com>, "Jim Hendler" <hendler@cs.umd.edu>, "Dan Connolly" <connolly@w3.org>, <www-rdf-logic@w3.org>



> Hi Folks,
> 
> In the OWL Reference Version 1.0 document it defines TransitiveProperty
> and SymmetricProperty as a subClassOf owl:ObjectProperty.
> 
> On the other hand, it defines FunctionalProperty as a subClassOf
> rdf:Propery.
> 
> What is the reason for this?  Why isn't FunctionalProperty also defined
> as a subClassOf owl:ObjectProperty?  
> 
> Thanks!  /Roger
> 

In mathematics, TransitiveProperty and SymmetricProperty should be a binary relation on a domain. In other words, the rdfs:domain and rdfs:range of these kind of properties should be same. In addition, the relationships between datatypes is supposed to be defined by XML Schema, not by RDFS or OWL. So, It's fine to define TransitiveProperty and SymmetricProperty as a subClassOf owl:ObjectProperty.

On the other hand, it's useful to define a relationship from an object type to a datatype as a functional property. So the rdfs:range of a FunctionalProperty could be a datatype, that's the reason why FunctionalProperty is specified as a subClassOf rdf:Property ( not owl:ObjectProperty).

In sum, it's reasonable to do so. 

Yuzhong Qu
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Dept. of Computer Science and Engineering
Southeast University, Nanjing 210096, P. R. China
Home Page: http://cse.seu.edu.cn/People/yzqu/en
Research Group: http://xobjects.seu.edu.cn
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Received on Tuesday, 4 March 2003 20:51:50 GMT

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