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Some basic questions about OWL-Full

From: Michael Schneider <schneid@fzi.de>
Date: Mon, 22 Oct 2007 22:06:40 +0200
Message-ID: <0EF30CAA69519C4CB91D01481AEA06A04A8758@judith.fzi.de>
To: "Owl Dev" <public-owl-dev@w3.org>

Hi!

OWL-Full has ever been a complete mystery to me, and I admit that I have
never really made an approach to explore it. But now that people have
started to work on a new version of OWL, I think it is a good time for me to
at least try to learn a few fundamental facts. So dear OWL-Full experts: I
will put a few questions, all very basic, and all of them can be answered by
just saying "yes" or "no". But I won't bite you if you also add a small
explanation to each of your answers. :)

(1) My first question is about syntactically correct OWL-Full ontologies. I
always thought that simply "everything" is allowed in OWL-Full. So my
question: Is every RDF graph an allowed OWL-Full ontology?

(2) The rest of my questions all deal with semantics. I think I have heard
somewhere that one can "change the semantics" of OWL-Full itself by stating
axioms about OWL vocabulary, but I don't know if this is true, and not even
what this exactly means. Ok, let's test this by creating a concrete example!
I would have said that the following two statements lead to inconsistency
even in OWL-Full:

  :x owl:sameAs :y .
  :x owl:differentFrom :y .

But what if I add the following axiom:

  EquivalentProperties(owl:sameAs owl:differentFrom)

This should at least be syntactically ok in OWL-Full (see (1)). But have I
also managed to make this ontology semantically consistent with this trick?
I don't believe so, but I am also not certain. And whatever answer is
correct, I do not have an explanation for any of them.

(3) A more general question: Is it true that whenever an OWL-DL ontology is
inconsistent under OWL-DL semantics, then it is also inconsistent under
OWL-Full semantics? Would sound reasonable to me, but I am not sure.

(4) Looking at both questions (2) and (3) brings me to my last question. The
ontology in question (2) is *not* an allowed OWL-DL ontology, of course, but
it contains a sub-ontology which is syntactically allowed in OWL-DL: The
first two statements above. So I ask if the following claim is true: "Given
that an OWL-Full ontology contains an OWL-DL sub-ontology, which is
inconsistent under OWL-DL semantics, then the complete OWL-Full ontology is
inconsistent under OWL-Full semantics." Is this true or wrong?

Ok, I think that this is enough for me for the moment to get a first feeling
for OWL-Full.

Cheers,
Michael

--
Dipl.-Inform. Michael Schneider
FZI Forschungszentrum Informatik Karlsruhe
Abtl. Information Process Engineering (IPE)
Tel  : +49-721-9654-726
Fax  : +49-721-9654-727
Email: Michael.Schneider@fzi.de
Web  : http://www.fzi.de/ipe/eng/mitarbeiter.php?id=555

FZI Forschungszentrum Informatik an der Universität Karlsruhe
Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe
Tel.: +49-721-9654-0, Fax: +49-721-9654-959
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Vorstand: Rüdiger Dillmann, Michael Flor, Jivka Ovtcharova, Rudi Studer
Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus
Received on Monday, 22 October 2007 20:07:02 GMT

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