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ISSUE 5.2 Language Compliance Levels - proposed clarification

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Thu, 23 Jan 2003 21:27:50 +0100
To: www-webont-wg@w3.org
Message-Id: <200301232127.50210.jjc@hpl.hp.com>


As actioned, probably for next week's telecon.
A backwardly incompatible clarification ...

PROPOSE:
  - to reopen issue 5.2
  - to retract the endorsement of existing OWL lite language subset.
  - to endorse the existing OWL Lite language subset in the OWL Overview of  
20 Jan 2003
http://lists.w3.org/Archives/Public/www-webont-wg/2003Jan/att-0327/01-OWLOverview
 -  to remove modality = complete from the OWL Lite Class Axioms in the 
Abstract Syntax
 -  to close issue 5.2

===

Rationale

As argued in [1] there is an apparant contradiction between our documents 
which is resolved with this change.
Moreover, as seen in [2] the modality = complete offers surprising expressive 
power.

[1]
http://lists.w3.org/Archives/Public/www-webont-wg/2003Jan/0363.html
[2]
http://lists.w3.org/Archives/Public/www-webont-wg/2003Jan/0401.html

===

Subissue - this proposed change is the smallest textual change (removes 11 
characters) to resolve the conflict but it also removes the following type of 
example from OWL Lite

<owl:Class rdf:ID="Husbands1">
<!-- NB *same* -->
   <owl:sameClassAs>
      <owl:Restriction>
         <owl:onProperty>
            <owl:ObjectProperty rdf:ID="wife"/>
            <owl:minCardinality
rdf:datatype="&xsd;int">1</owl:minCardinality>
         </owl:onProperty>
      </owl:Restriction>
   </owl:sameClassAs>
</owl:Class>


I would like to hear if anyone would like to speak in favour of being able to 
name Restrictions in owl:Lite.
The example can be changed to use someValuesFrom allValuesFrom or a different 
0 or 1 cardinality constraint.

What is still possible in owl:Lite is something like:

<owl:Class rdf:ID="Husbands2">
<!-- NB *sub* -->
   <rdfs:subClassOf>
      <owl:Restriction>
         <owl:onProperty>
            <owl:ObjectProperty rdf:ID="wife"/>
            <owl:minCardinality
rdf:datatype="&xsd;int">1</owl:minCardinality>
         </owl:onProperty>
      </owl:Restriction>
   </rdfs:subClassOf>
</owl:Class>

The difference between these is that given a KB with a triple:

<Jeremy> <wife> <Chiara> .

we can entail

<Jeremy> rdf:type <#Husbands1> .

but we cannot entail

<Jeremy> rdf:type <#Husbands2>


OWL Lite retains the ability to use owl:sameClassAs between two named classes.


Jeremy





               
Received on Thursday, 23 January 2003 15:27:25 GMT

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