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Comment on POWDER WDR, 2008-06-30: exact translation of descriptorset into POWDER-S

From: Ivan Herman <ivan@w3.org>
Date: Thu, 03 Jul 2008 15:36:00 +0200
Message-ID: <486CD5C0.6030407@w3.org>
To: public-powderwg@w3.org
Comment on http://www.w3.org/TR/2008/WD-powder-dr-20080630/

Looking at examples 2.2 and 2.3 and the way it is translated into 
POWDER-S: the translation is an intersection of restrictions:

<owl:Class rdf:nodeID="descriptorset_1">
27      <owl:intersectionOf rdf:parseType="Collection">
28        <owl:Restriction>
29          <owl:onProperty rdf:resource="http://example.org/vocab#color" />
30          <owl:hasValue>red</owl:hasValue>
31        </owl:Restriction>
32        <owl:Restriction>
33          <owl:onProperty rdf:resource="http://example.org/vocab#shape" />
34          <owl:hasValue>square</owl:hasValue>
35        </owl:Restriction>
36      </owl:intersectionOf>
37      <dc:description>Everything on example.org is red and 
38      <foaf:depiction rdf:resource="http://example.org/icon.png" />
39    </owl:Class>

what this means, strictly speaking, is that if I take an instance of 
that class, the 'color' or 'shape' properties will take that specified 
values _if they are applied_. However, it does _not_ say that this 
property _is_ applied on those instances. If the intention of the spec 
is to say 'this and this property _is_ applied and it has this and this 
value', then an extra cardinality restriction for each of those 
properties might be necessary... It is up to the group to decide what 
the intention is, though.



Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf

Received on Thursday, 3 July 2008 13:36:32 UTC

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