RE: owl:Thing in RL profile?

Hello,

I seem to remember that we explicitly excluded owl:Thing from OWL 2 RL, on the
account that it is difficult to support in OWL 2 RL/RDF. The objection there was
that the extension of owl:Thing would become very large. As a consequence, the
rules axiomatizing owl:Thing were removed from OWL 2 RL/RDF; but then, to make
Theorem PR1 hold, we removed owl:Thing from OWL 2 RL as well.

I'm not 100% sure of this, but it seems to me that this is what happened.

Regards,

Boris

> -----Original Message-----
> From: Michael Schneider [mailto:schneid@fzi.de]
> Sent: 12 August 2009 23:44
> To: mak@aifb.uni-karlsruhe.de
> Cc: W3C OWL Working Group; Bernardo Cuenca Grau; Boris Motik; Ian Horrocks;
> Zhe Wu; Achille Fokoue
> Subject: RE: owl:Thing in RL profile?
> 
> 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 Thursday, 13 August 2009 06:43:10 UTC