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shorthand notation for OWL Lite constraints

From: Christopher Welty <welty@us.ibm.com>
Date: Thu, 10 Oct 2002 10:06:50 -0400
To: www-webont-wg@w3.org
Message-ID: <OFAEBE1B95.D5E3EC48-ON85256C4E.004D051A@pok.ibm.com>

The working group considered at length suggestions from outside the group 
to give explicit names to the limited set of cardinality restrictions 
available in <OWL Lite>, in particular:

Cardinality 1: hasExactlyOne
MaxCardinality 1: hasAtMostOne
MinCardinality 1: hasAtLeastOne
MaxCardinality 0: hasNo

This leads to "more natural" and shorter expressions of the four possible 
<OWL Lite> cardinality restrictions.  For example, to say a soccer team 
has one and only one goalie in <OWL Lite>:

<owl:class rdf:ID=SoccerTeam>
  <rdfs:subClassOf>
   <owl:restriction>
    <owl:onProperty rdf:resource="goalie"/>
    <owl:cardinality>1</owl:cardinality>
   </owl:restriction>
 </rdfs:subClassOf>
</owl:class>

With the shorthand notation described above, one could say instead:

<owl:class rdf:ID=SoccerTeam>
  <rdfs:subClassOf>
   <owl:hasExactlyOne rdf:resource="goalie"/>
  </rdfs:subClassOf>
</owl:class>

At the fourth f2f meeting in Bristol, the working group decided that the 
issue was one of presentation, not of functionality or semantics of the 
language.  Adding these shorthand constructors places an additional burden 
on the RDF triple interpretation, because it adds a new <i>class</i> of triple constructs to the semantics, which is nearing the final stage.  
It seemed clear to a majority of members that presentation tools, i.e. 
tools that are used to edit and display OWL ontologies, could easily allow 
for such shorthand notation, and the group resolved not to add it to the 
language.



Dr. Christopher A. Welty, Knowledge Structures Group
IBM Watson Research Center, 19 Skyline Dr.
Hawthorne, NY  10532     USA 
Voice: +1 914.784.7055,  IBM T/L: 863.7055
Fax: +1 914.784.6078, Email: welty@us.ibm.com
Received on Thursday, 10 October 2002 10:07:26 GMT

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