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properties as the range of properties...

From: Terry R. Payne <terryp@cs.cmu.edu>
Date: Thu, 7 Mar 2002 19:24:34 -0500
To: www-rdf-logic@w3.org
Cc: Massimo Paolucci <paolucci@cs.cmu.edu>
Message-ID: <IKEELLHOLAFLDDAOCOGHIEEBCMAA.terryp@cs.cmu.edu>
We're trying to determine if it is valid to define a property
who's range is also a property; for example:

  <daml:Property rdf:ID="refersTo">
    <daml:domain rdf:resource="&daml;#Class"/>
    <daml:range  rdf:resource="&daml;#Property"/>
  </daml:Property>

This feels intuitively wrong, as, if one were to draw the graph,
one then has an arc who's range is an arc.

However, a property *is* defined in the DAML ontology [1] as a
class.  In addition,  the dfinition of the property "samePropertyAs"
(defined in [1]) would also have a range as a Property (as defined
by the superproperty "subPropertyOf" defined in [2]).

  <!-- from http://www.daml.org/2001/03/daml+oil -->
  <Property rdf:ID="samePropertyAs">
    <rdfs:label>samePropertyAs</rdfs:label>
    <rdfs:comment>
      for samePropertyAs(P, R), read P is an equivalent property to R.
    </rdfs:comment>
    <rdfs:subPropertyOf rdf:resource="#equivalentTo"/>
    <rdfs:subPropertyOf
rdf:resource="http://www.w3.org/2000/01/rdf-schema#subPropertyOf"/>
  </Property>

  <!-- from http://www.w3.org/2000/01/rdf-schema -->
  <rdf:Property ID="subPropertyOf">
    <rdfs:label xml:lang="en">subPropertyOf</rdfs:label>
    <rdfs:label xml:lang="fr">sousPropri&#233;t&#233;De</rdfs:label>
    <rdfs:comment>Indicates specialization of properties</rdfs:comment>
    <rdfs:range
rdf:resource="http://www.w3.org/1999/02/22-rdf-syntax-ns#Property"/>
    <rdfs:domain
rdf:resource="http://www.w3.org/1999/02/22-rdf-syntax-ns#Property"/>
  </rdf:Property>

So perhaps it would be valid afterall????

	Terry

[1] http://www.daml.org/2001/03/daml+oil
[2] http://www.w3.org/2000/01/rdf-schema

_____________________________________________________________________
Terry R. Payne, PhD.    | http://www.cs.cmu.edu/~terryp/index.html
CMU, Robotics Institute | Voice: (412) 268-8780 Fax: (412) 268-5569
Pittsburgh, PA 15213    | Email: terry@acm.org or Terry.Payne@cmu.edu
Received on Thursday, 7 March 2002 19:26:56 GMT

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