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Re: When to use object property vs datatype property

From: Toby A Inkster <tai@g5n.co.uk>
Date: Sun, 19 Jul 2009 09:15:53 +0100
Message-Id: <E15714D1-53FB-437D-A47F-0EE7A7D724D7@g5n.co.uk>
Cc: <semantic-web@w3.org>
To: kj@iteegosearch.com
On 19 Jul 2009, at 07:40, Kevin Jenkins wrote:

> Itís my understanding that object properties link individuals via a  
> property and that datatype properties link individuals to data  
> (such as form input). [...] I have many properties in my ontology  
> such as has-company-name, has-software-product, is-employee-of etc  
> Ö my guess is these must be datatype properties because somewhere  
> (I guess a web form) somebody has to name the company, choose the  
> software product category from a list, indicate who the employer is  
> etc.


That's not correct.

An object property is a property that takes a resource (an object) as  
its value. A datatype property is a property that takes a literal  
(string, number, date/time, boolean, etc) as its value.

e.g.

<#kj> rdf:type foaf:Person ;
       foaf:name "Kevin Jenkins" ;
       foaf:mbox <mailto:kj@iteegosearch.com> ;
       foaf:mbox_sha1sum "d610935545bb79ad673d5a5e7bd45a11f9b12128" ;
       foaf:knows <#alice> .

In the above, foaf:mbox and foaf:knows are object properties, while  
foaf:name and foaf:mbox_sha1sum are datatype properties. (rdf:type is  
also logically an object property, though I think OWL treats it as a  
special case.)

-- 
Toby A Inkster
<mailto:mail@tobyinkster.co.uk>
<http://tobyinkster.co.uk>
Received on Sunday, 19 July 2009 08:14:58 UTC

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