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Re: Defining a property to have an EMPTY range?

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 14 May 2003 09:00:35 -0400 (EDT)
Message-Id: <20030514.090035.42670015.pfps@research.bell-labs.com>
To: costello@mitre.org
Cc: www-rdf-interest@w3.org

From: "Roger L. Costello" <costello@mitre.org>
Subject: Defining a property to have an EMPTY range?
Date: Wed, 14 May 2003 08:31:37 -0400

> Hi Folks,
> It dawned on me today that there are times when it may be useful to
> state in an RDF Schema document (or an OWL document) that 
>    "the range of this property is EMPTY"
> Example: I would like to be able to "tag" a Document with a security
> classification, e.g.,
>    <Document>
>        <secret/>
>        <content>
>            ...
>        </content>
>    </Document>
> Note the <secret/> property.  Its purpose it simply to "tag" this
> Document as having a secret classification.
> Thus, in an RDF Schema (or OWL document) I would like to state:
>     <rdf:Property rdf:ID="secret">
>         <rdfs:domain rdf:resource="#Document"/>
>         <rdfs:range rdf:resource="EMPTY"/>
>     </rdf:Property>
> Obviously, this is not correct, as there is no EMPTY in RDF (or OWL).
> Am I looking at this incorrectly?  How would you do this?  What are your
> thoughts?  /Roger

I think that you are asking for the ability to have a property value with
no value.  This is not possible in the underlying representational
philosophy of RDF (and OWL).

You can get close, however, in one of two ways.

1/ You can create a class with one element, via

	EnumeratedClass(foo bar)

   and then use a property whose range is that class, as in

	ObjectProperty(what range(foo))
	Individual(mil value(what foo))

2/ You can use a class instead of a property, as in

	Class(secret partial super(document))

	Individual(mil type(secret))

Peter F. Patel-Schneider
Bell Labs Research
Lucent Technologies

Received on Wednesday, 14 May 2003 09:00:44 UTC

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