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RE: owl:Thing in RL profile?

From: Michael Schneider <schneid@fzi.de>
Date: Thu, 13 Aug 2009 00:44:19 +0200
Message-ID: <0EF30CAA69519C4CB91D01481AEA06A0015DE2A4@judith.fzi.de>
To: <mak@aifb.uni-karlsruhe.de>
Cc: "W3C OWL Working Group" <public-owl-wg@w3.org>, "Bernardo Cuenca Grau" <Bernardo.Cuenca.Grau@comlab.ox.ac.uk>, "Boris Motik" <boris.motik@comlab.ox.ac.uk>, "Ian Horrocks" <ian.horrocks@comlab.ox.ac.uk>, "Zhe Wu" <alan.wu@oracle.com>, "Achille Fokoue" <achille@us.ibm.com>
Hi!

Markus Krötzsch wrote:

>Bothering you again with the below question. If this is a bug we should
>probably get it fixed soon. -- Markus
>
>On Samstag, 8. August 2009, Markus Krötzsch wrote:
>> The forwarded email below asks the question whether assertions of the
>> form
>>
>> ClassAssertion(owl:Thing auto)
>>
>> are allowed in OWL RL. They seem to be excluded by the grammar, but
>> maybe this is a bug rather than deliberate design.

Hm, maybe I'm missing something (it's much too late in the day, literally
:)), but it looks to me that this would break theorem PR1 [1]. For example,
look at the graphs

G1 := {
  ex:o rdf:type owl:Ontology .
  ex:drivenBy rdf:type owl:ObjectProperty .
  ex:auto ex:drivenBy ex:alice .
}

G2 := { 
  ex:o rdf:type owl:Ontology .
  ex:auto rdf:type owl:Thing .
}

With owl:Thing being allowed to appear as classes in class assertions, the
reverse RDF mappings for both G1 and G2 would be in the OWL 2 RL syntactic
fragment, and the pair <G1,G2> would satisfy the premises of PR1. Further,
G1 direct entails G2. But G2 cannot be inferred from G1 via the OWL 2 RL/RDF
rules. 

Of course, this could as well be considered a problem with PR1, or with the
RL/RDF rules...

Good night,
Michael

[1] <http://www.w3.org/2007/OWL/wiki/Profiles#Theorem-PR1>

>>If not, we need to revisit
>> profile classifications of some test cases.
>>
>> Feedback (esp. by the Profiles editors) is welcome.
>>
>> Thanks,
>>
>> Markus

--
Dipl.-Inform. Michael Schneider
Research Scientist, Dept. Information Process Engineering (IPE)
Tel  : +49-721-9654-726
Fax  : +49-721-9654-727
Email: michael.schneider@fzi.de
WWW  : http://www.fzi.de/michael.schneider
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Received on Wednesday, 12 August 2009 22:45:01 GMT

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