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RE: Layering bug?

From: Mehrdad Omidvari <Mehrdad.Omidvari@networkinference.com>
Date: Thu, 3 Jul 2003 13:14:00 +0100
Message-ID: <3BE4D3F0FB726240966DEF40418472B55FE1@ni-lon-server1.ad.networkinference.com>
To: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
Cc: <www-webont-wg@w3.org>


I think your new example is wrong in both OWL Full and DL.
There is nothing stopping a "property" to be empty. For example you
could assert that the domain of q is owl:Nothing. This would not make
the ontology inconsistent. Property q is not necessarily equivalent to
p, as q could be empty.

Also in your first example asserting property relations between classes
is not OWL DL:

    <owl:ObjectProperty rdf:ID="p" />
    <owl:Class rdf:ID="c" >
       <p>
         <owl:Class rdf:ID="d" />
       </p>
    </owl:Class>

I think an OWL DL parser should throw an exception parsing the above. In
OWL DL, property relations can be asserted between individuals and not
classes.

I understand that you are trying to come up with an example which is a
legal OWL DL ontology and an entailment which can be expressed in OWL DL
but not valid in OWL DL (but valid in OWL Full).
As the semantics of OWL DL is stricter than that of OWL Full, it might
not be possible to come up with such an example.

Mehrdad Omidvari

-----Original Message-----
From: Jeremy Carroll [mailto:jjc@hplb.hpl.hp.com] 
Sent: 03 July 2003 12:10
To: Jeremy Carroll
Cc: www-webont-wg@w3.org
Subject: Re: Layering bug?





Jeremy Carroll wrote:

> 
> 
> How about this:
> 
> eg:c rdf:type owl:Class .
> eg:d rdf:type owl:Class .
> eg:ap rdf:type AnnotationProperty .
> owl:Thing owl:oneOf rdf:nil .
> 
> entails
> 
> eg:c eg:ap eg:d .
> 
> 
> ====
> 
> I think this holds in OWL Full but not in OWL DL, yet it is within the
> syntactic subset.



As Mehrdad points out this is actually an OWL DL entailment,
since owl:Thing is non-empty.

Updated problem case is:


eg:p rdf:type owl:ObjectProperty .
eg:q rdf:type owl:ObjectProperty .
owl:Thing owl:oneOf _:b .
   _:b rdf:first eg:i .
   _:b rdf:rest rdf:nil.
   eg:i rdf:type owl:Thing.
eg:i eg:p eg:i .

  entails

eg:i eg:q eg:i .

True in OWL full, since the universe has only one element thus eg:q and 
eg:p are the same property.

False in OWL DL.

Jeremy
Received on Thursday, 3 July 2003 08:14:08 GMT

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