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Re: Semantics question (was Re: XSLT question)

From: Stasinos Konstantopoulos <konstant@iit.demokritos.gr>
Date: Wed, 23 Apr 2008 03:30:07 +0300
To: Phil Archer <parcher@icra.org>
Cc: Public POWDER <public-powderwg@w3.org>
Message-ID: <20080423003007.GD5492@iit.demokritos.gr>

On Tue Apr 22 17:57:45 2008 Phil Archer said:

> <descriptorset>
>   <icra:na>1</icra:na>
>   <icra:vj>1</icra:vj>
>   <bbfc:rating rdf:resource="http://www.bbfc.org/1997/#12" />
> </descriptorset>
> 
> [...] become this in POWDER-S:
> 
> <owl:Class rdf:nodeID="descriptorset_1">
>   <owl:intersectionOf rdf:parseType="Collection">
>     <owl:Restriction>
>       <owl:onProperty rdf:resource="&icra;#na" />
>       <owl:hasValue>true</owl:hasValue>
>     </owl:Restriction>
>     <owl:Restriction>
>       <owl:onProperty rdf:resource="&icra;#vj" />
>       <owl:hasValue>true</owl:hasValue>
>     </owl:Restriction>
>     <*owl:Class* rdf:resource="http://www.bbfc.org/1997/#12" />
>   </owl:intersectionOf>
> </owl:Class>
> 
> So the ICRA descriptors (which have literal values) would become 
> property restrictions on the OWL class. The BBFC rating becomes another 
> class and the descriptor set is the intersection of all three.
> 
> The use of rdf:resource tells the processor that the referred to item is 
> an RDF (or OWL) class and not another POWDER (XML) descriptor set. For 
> that we'd use ref, i.e.
> 
> <descriptorset>
>   <icra:na>1</icra:na>
>   <icra:vj>1</icra:vj>
>   <bbfc:rating ref="http://www.bbfc.org/1997/#12" />
> </descriptorset>
> 
> Now that becomes something different in POWDER-S because we're referring 
> to something else that is a description but that is not an RDF or OWL 
> class - it could be anything, hence this would become
> 
> <owl:Class rdf:nodeID="descriptorset_1">
>   <owl:intersectionOf rdf:parseType="Collection">
>     <owl:Restriction>
>       <owl:onProperty rdf:resource="&icra;#na" />
>       <owl:hasValue>true</owl:hasValue>
>     </owl:Restriction>
>     <owl:Restriction>
>       <owl:onProperty rdf:resource="&icra;#vj" />
>       <owl:hasValue>true</owl:hasValue>
>     </owl:Restriction>
>   </owl:intersectionOf>
>   <*rdfs:seeAlso* rdf:resource="http://www.bbfc.org/1997/#12" />
> </owl:Class>
> 
> This class still has the ICRA property restrictions but now just says 
> 'take a look over there as well' but the BBFC rating is not part of the 
> actual description.

If the BBFC vocabulary is really RDF then bbfc:12 cannot be anything, it
has to be a either a class, an instance, or a relation. If one can
resolve bbfc: then it becomes obvious what 12 is, and in any case the
POWDER author will have to know what it really is and use it
appropriately (see previous email). I guess the rdfs:seeAlso allows one
to not have to know, but then is should be expressed by a similarly
agnostic construct in POWDER/XML. If one writes:
  <bbfc:rating ref="http://www.bbfc.org/1997/#12" />
in POWDER/XML, one has already made the commitment that bbfc:rating is a
property and bbfc:12 is an instance which is our resource's value for
the bbfc:rating property.

s
Received on Wednesday, 23 April 2008 00:30:50 GMT

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