RE: RDF/XML shorthand for RDF reification

Hi Peter!

Peter F. Patel-Schneider wrote:

>I'm not sure that I believe this.
>
>I think that one consequence of using the shorthand would be that an
>annotated axiom might not entail itself in OWL Full.
>
>For example, how would one arrange it so that
>
>SubClass(Label("Foo") A B)
>
>entails
>
>SubClass(Label("Foo") A B)
>
>in the OWL Full arena?

I am not certain that I correctly understand the question. In general (by
Simple Semantics) every RDF graph entails itself. So as long as a DL axiom
has a mapping to RDF, the respective RDF graph entails itself in OWL Full.

In the case of your example axiom above, the RDF mapping would be (but using
a URI instead of a bNode for the axiom):

  ex:axiom rdf:type owl:Axiom 
  ex:axiom rdf:subject A
  ex:axiom rdf:property rdfs:subClassOf
  ex:axiom rdf:object B
  ex:axiom rdfs:label "Foo"^^xsd:string

The RDF/XML serialization would be pretty compact in this case, but this is
has no impact on OWL Full, which only deals with the (abstract) RDF graph.

>peter

Cheers,
Michael 

>From: Alan Ruttenberg <alanruttenberg@gmail.com>
>Subject: Re: RDF/XML shorthand for RDF reification
>Date: Tue, 1 Jul 2008 07:11:54 -0400
>
>> On Jun 26, 2008, at 7:16 AM, Peter F. Patel-Schneider wrote:
>>
>> > 2/ Changing to named nodes would change the OWL Full semantics.  A
>> >    careful check would have to be made to see whether any
>interesting or
>> >    useful inferences could change.
>>
>>
>> According to Michael this is one not a problem. I'm still thinking
>about issue 1/.
>>
>> He says:
>>
>> > Short answer: There are no additional consequences for OWL Full.
>> >
>> > Longer answer: Just have a look at the OWL Full Wiki:
>> >
>> >   <http://www.w3.org/2007/OWL/wiki/
>> > FullSemanticsAxiomAnnotations#Semantics>
>> >
>> > The "Main semantic condition" there is applicable to both cases,
>with a bNode
>> > or with an URI at the LHS. That's not because I wanted to make this
>semantic
>> > condition more general as in OWL DL - I promise that I always try
>hard to be
>> > as close to the DL semantics as possible. The point is that in an
>RDF
>> > compatible semantics, it is not possible to restrict axioms to such
>RDF graphs
>> > which only have a bNode as their LHS. This would be a syntactic
>restriction,
>> > which is not possible in OWL Full - which is a major distinction
>between OWL
>> > Full and OWL DL.
>> >
>> > So this whole current discussion about named axioms is really only
>an OWL DL
>> > topic. It's the question whether to extend the reverse RDF mapping
>to cases,
>> > where the LHS of an axiom annotation may be an URI, or not. OWL Full
>is
>> > completely indifferent about this question. In particular, in my
>current
>> > proposal, you will always receive the axiom triple as a result,
>whether the
>> > LHS node is a bNode or a URI.