Re: Axiomatic triples in OWL-R-Full?

Michael Schneider wrote:
> Hi, Ivan!
> 
> This is a good observation, and I think an issue should be raised for it.

Maybe we should decide on the group this evening whether this should be 
entered as an Issue

> 
> The question whether to include axiomatic triples or not depends on whether we want the semantics of OWL R Full to be an upper semantics of RDFS or not.
> 
> Just one technical/theoretical remark for the moment: To receive strict RDFS compatibility, it is necessary to include all of the following axiomatic triples, for every natural language n:
> 

My understanding of Horst's paper is that _for a given graph_ 
calculating the RDFS closure (ie, by induction, the OWL-R-Full closure, 
too) is doable because one can add only those rdf:_n related axiomatic 
triples by limiting 'n' to the highest occurrence of an rdf:_i usage in 
the original graph. I may have missed something in fine print in the 
paper, but my understanding is that this is perfectly doable, proper, 
and we would then get back to a safe, finite world.

But I yield to your knowledge of RDFS semantics...

Ivan


> From RDF semantics:
> 
>    rdf:_n rdf:type rdf:Property
> 
> From RDFS semantics:
> 
>    rdf:_n rdf:type rdfs:ContainerMembershipProperty
>    rdf:_n rdfs:domain rdfs:Resource
>    rdf:_n rdfs:range rdfs:Resource
> 
> Obviously, these are *infinitely* many axiomatic triples. In practice this would mean that complete OWL R Full conformance would probably not be possible to achieve. So it would be up to the implementors to decide about the intended conformance level of their product.
> 
> Cheers,
> Michael
> 
> Ivan Herman wrote:
> 
>> (This may have to be raised as a more formal ISSUE. Also: it 
>> is _not_ my 
>> intention to get this problem solved before the upcoming 
>> publication round!)
>>
>> The current OWL-R-Full does not include 'axiomatic triples' to 
>> be added 
>> to the resulting graph. What I mean is to add triples like
>>
>> (owl:FunctionalProperty,rdfs:subClassOf,rdf:Property)
>> (rdfs:subPropertyOf,rdfs:domain,rdf:Property)
>>
>> etc. See for the RDF Semantics for a bunch of those in RDFS, 
>> and Horst's 
>> paper on pD* for their OWL equivalents.
>>
>> I am not saying we must have those; this is clearly touching upon the 
>> issue whether the core RDF/RDFS/OWL vocabulary is an object of 
>> discourse 
>> or not in OWL-R-Full. We _could_ therefore, explicitly say that those 
>> axiomatic triples are not defined in OWL-R-Full. That would mean that 
>> some (valid) RDFS or OWL Full entailements are not meaningful in 
>> OWL-R-Full, ie, OWL-R is also defined as a syntactic 
>> restriction v.a.v. 
>> OWL 2 Full and not only OWL 2 DL.
>>
>> Again, I am not saying this is wrong. But the decision should be made 
>> explicitly and documented in the profile document as well. 
>> Alternatively, we could add those axiomatic triples for 
>> OWL-R-Full (but 
>> then the relationship between OWL-R-Full and OWL-R-DL becomes 
>> less clear...)
>>
>> Ivan
>>
>>
>> -- 
>>
>> Ivan Herman, W3C Semantic Web Activity Lead
>> Home: http://www.w3.org/People/Ivan/
>> PGP Key: http://www.ivan-herman.net/pgpkey.html
>> FOAF: http://www.ivan-herman.net/foaf.rdf
>>
> 
> --
> Dipl.-Inform. Michael Schneider
> FZI Forschungszentrum Informatik Karlsruhe
> Abtl. Information Process Engineering (IPE)
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> Email: Michael.Schneider@fzi.de
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> 
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-- 

Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf