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Re: Semantics question (was Re: XSLT question)

From: Stasinos Konstantopoulos <konstant@iit.demokritos.gr>
Date: Wed, 23 Apr 2008 14:10:32 +0300
To: Phil Archer <parcher@icra.org>
Cc: Public POWDER <public-powderwg@w3.org>
Message-ID: <20080423111032.GB28276@iit.demokritos.gr>

On Wed Apr 23 11:58:17 2008 Phil Archer said:

> OK, thanks very much Stasinos, that's hugely helpful. I've worked (and  
> re-worked) through your comments on all this and would like to propose  
> the following which, I hope, is in line with what you have said and, no  
> less important, can be encoded in the XSLT that Kev is working on right 
> now.
> I've prepared several examples of POWDER descriptor sets and their  
> equivalent DR-S versions. Logically they begin with a simple one and end  
> up hideously complex just to prove that the same rules can be applied  
> and yield a consistent answer.
> So, the simple one first:

[snipped lots of easy calls]

> If the value of a property is a class then we have this situation:
> <descriptorset>
>   <ex:property1>value</ex:property1>
>   <ex:property2
>       rdf:resource="http://example.org/semantic/powder.rdf#d1" />
> </descriptorset>

But that was the whole point: the value of a property *cannot* be a
class, it *has* to be in an instance.

> Which generates:
> <owl:Class rdf:nodeID="descriptorset_1">
>   <owl:intersectionOf rdf:parseType="Collection">
>     <owl:Restriction>
>       <owl:onProperty rdf:resource="&ex;property1" />
>       <owl:hasValue>value</owl:hasValue>
>     </owl:Restriction>
>     <owl:Restriction>
>       <owl:onProperty rdf:resource="&ex;property2" />
>       <owl:hasValue
>          rdf:resource="http://example.org/semantic/powder.rdf#d1" />
>     </owl:Restriction>
>   </owl:IntersectionOf>
> </owl:Class>

So, if "http://example.org/semantic/powder.rdf#d1" is of type
"owl:Class", then this fragment is *not* OWL.

seeAlso http://www.w3.org/TR/owl-ref/#hasValue-def:

  The value constraint owl:hasValue is a built-in OWL property that links
  a restriction class to a value V, which can be either an individual or a
  data value.

[snipped lots of stuff invalidated by the previous statement]

Received on Wednesday, 23 April 2008 11:11:33 UTC

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