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Error in OWL2-QL conformance test? (WebOnt-I5.26-010)

From: Barry Bishop <barry.bishop@ontotext.com>
Date: Wed, 27 Oct 2010 11:10:17 +0200
Message-ID: <4CC7EC79.8050808@ontotext.com>
To: public-owl-comments@w3.org
Hello,

I do not believe that:

    http://owl.semanticweb.org/page/TestCase:WebOnt-I5.26-010

is a valid OWL2-QL profile test. Below is the exchange between myself
and Michael Schneider on the subject.

I hope this helps somehow. Regards,
barry

-- 
Barry Bishop
OWLIM Product Manager
Ontotext AD
Tel: +43 650 2000 237
email: barry.bishop@ontotext.com
www.ontotext.com

-------- Original Message --------
Subject: RE: Another conformance question
Date: Wed, 27 Oct 2010 10:54:22 +0200
From: Michael Schneider <schneid@fzi.de>
To: Barry Bishop <barry.bishop@ontotext.com>
CC: Spas <pachob@gmail.com>

Hi Barry!

Barry Bishop wrote:

>We are creating a rule implementation for OWL2-QL (for no particular
>reason), but have found something odd in the conformance tests:
>
>http://owl.semanticweb.org/page/TestCase:WebOnt-I5.26-010
>
>Which is odd, because OWL 2 QL specifically states that it does not
>support minCardinality. Is this an error in the test, i.e. that it
>should not apply to QL?

Yes! While I am not so fluent with the syntactic restrictions of OWL 2
QL, I had a look in the spec at

  <http://www.w3.org/TR/2009/REC-owl2-profiles-20091027/#OWL_2_QL>

and found that minCardinality restrictions are (a) explicitly excluded
from QL in the Feature Overview (Sec. 3.1), and (b) do not appear in the
BNF for class expressions in Sec. 3.2.3.

Worse, having a closer look at the conclusion ontology, I can see that
it is not even valid OWL 2 DL! What you see there is simply a "dangling"
cardinality restriction, not part of any axiom.

When you press klick the "Convert syntax: functional" link, then you get
something very different, without the restriction expression anymore.
Looks like OWL API fails to detect the error and gets entirely confused.
Further, using the OWL 2 validator at

  http://owl.cs.manchester.ac.uk/validator/

claims that this is an OWL 2 QL ontology. It is not!

You should report this as an error to the comment mailing list at

    public-owl-comments@w3.org

I suggest to attach our discussion to the mail.

Cheers,
Michael

--
Dipl.-Inform. Michael Schneider
Research Scientist, 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 Wednesday, 27 October 2010 09:10:43 GMT

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