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Re: ISSUE 5.3 Semantic Layering

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Sun, 29 Jun 2003 21:41:31 +0300
To: www-webont-wg@w3.org
Message-Id: <200306292141.31886.jjc@hpl.hp.com>

>Jeremy wrote:
>> As a straw man, how effective would the following change to S&AS be:
>>
>> rewrite 5.3 so that:
>>
>> OWL Full neither affirms or denies that owl:Thing = rdfs:Resource,
>> owl:ObjectProperty = rdf:Property owl:Class = rdfs:Class (where = is
>> equality of class extension).

Jos:
>Jeremy, how does this fix
>http://lists.w3.org/Archives/Public/www-webont-wg/2003Jun/0295

This example I take to be:
[[
T(
> Class( <foo> annotation( <a> <bar> ) )
> AnnotationProperty( <a> )
> Class( <bar> )
)
OWL Full entails
T(
> AnnotationProperty( <a> )
> Class( <foo> annotation( <a> individual() ) )
)

because the individual() item is transformed into a bnode (with type 
owl:Thing?) and the type triple is trivially true, so that the OWL Full 
contentful part is:

<foo> <a> <bar> .
entails
<foo> <a> _:b .
]]

If I use the translation rules on individual() in an appropriate way I should 
get:
<foo> <a> <bar> .
entails
<foo> <a> _:b .
_:b rdf:type owl:Thing .

There may be bugs in the transformation rules that don't do that, although I 
believe Peter has made some changes there.
The entailment is now no longer content free unless owl:Thing is the same as 
rdfs:Resource.
In particular if we don't know that owl:Class rdfs:subClassOf owl:Thing then 
the entailment no longer follows.


Jeremy:
>> How much baby goes out with the bath water?

Peter:
>However, you would then need to assert, for example, that rdfs:Class was
an
>owl:Class before you would get many OWL inferences from it.  In essence,
>you would have to do all the same typing you need to do in OWL DL.

An example would be:

eg:foo rdf:type owl:Class .
eg:foo dc:creator "Jos" .
eg:madeByJos owl:equivalentClass _:r .
_:r rdf:type owl:Restriction .
_:r owl:onProperty dc:creator
_:r owl:hasValue "Jos" .


currently entails, but would not:

eg:foo rdf:type eg:madeByJos .

because restrictions intersections unions complements are scoped by owl:Thing, 
not rdfs:Resource, nor the universe.

Jeremy
Received on Sunday, 29 June 2003 15:41:44 GMT

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