RE: ACTION-103 are all OWL 1.0 ontologies representable in RDF

[cc'ed Alan, since I refer to him]

Hi Peter!

Peter F. Patel-Schneider wrote on Wednesday, March 12, 2008:

>From: "Michael Schneider" <schneid@fzi.de>
>Subject: RE: ACTION-103 are all OWL 1.0 ontologies representable in RDF
>Date: Wed, 12 Mar 2008 21:36:49 +0100
>
>> [related to ISSUE-100]
>> 
>> Hi Peter!
>> 
>> Here is a concrete example expression to check my understanding:
>> 
>>   ObjectProperty(http://example.org#foo)
>> 
>>   Class(http://example.org#foo partial 
>>         restriction(http://example.org#foo 
>>                     value(http://example.org#foo) ) )
>> 
>> My questions:
>> 
>> (A) Is this expression syntactically valid in OWL-1.0 
>Abstract Syntax?
>
>Close enough.  :-)
>
>> (B) Is this expression transformable to RDF by means of the 
>OWL-1.0 RDF
>> mapping?
>
>Yes, as every OWL 1.0 DL ontology is transformable.  

Indeed! I was confused by this answer last week. But you are right, of course: The RDF mapping actually works on /every/ OWL-DL ontology in abstract syntax form.

I remember that Alan has talked about a kind of "roundtripping problem", probably with the idea that it is possible to map from abstract syntax to RDF, but not back in every case. But I think this isn't a perfectly adequate characterization of the situation here. In OWL-DL, there is no reverse mapping, there is just an RDF mapping. And if this RDF mapping allows to travel from abstract syntax to RDF, then, trivially, there is also a way back again, and the result of this "round trip" will always be the original OWL-DL ontology in abstract syntax form.

However, what this mapping alone doesn't give an answer to is the question whether the result of the mapping of an OWL-DL ontology in abstract syntax form is in every case also an /OWL-DL ontology in RDF graph form/. The latter term is defined in sec. 4.2 of the AS&S:

  <http://www.w3.org/TR/owl-semantics/mapping.html#4.2>

  "An RDF graph is an OWL DL ontology in RDF graph form 
  if it is equal [...] to a result of the transformation 
  to triples [...] of a collection of OWL DL ontologies 
  and axioms and facts in abstract syntax form 
  that has a separated vocabulary."

>> (C) Is this expression a legal OWL-1.0-DL ontology?
>
>If it is syntactically valid, then it is legal.

So the question, which I should better have been asking for, was (following question C):

  (D) Is there an OWL-DL ontology in RDF graph form,
      which corresponds (by means of the RDF mapping) 
      to the above OWL-DL ontology in abstract syntax form?

And the answer to (D) is "no", simply because my example ontology is an OWL-DL ontology in abstract syntax form, which does *not* have a separated vocabulary.

The question here is of course: Is this just play on words? Or have there been any technical considerations which have eventually lead to the situation that non-separated vocabularies (i.e. punning) were allowed for "OWL-DL ontologies in abstract syntax form", but not for "OWL-DL ontologies in RDF graph form"?

>> Regards,
>> Michael
>
>peter

All the best,
Michael

--
Dipl.-Inform. Michael Schneider
FZI Forschungszentrum Informatik Karlsruhe
Abtl. Information Process Engineering (IPE)
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