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Re: ISSUE-79 (EL++): REPORTED: EL++ Variants

From: Carsten Lutz <clu@tcs.inf.tu-dresden.de>
Date: Thu, 29 Nov 2007 08:30:19 +0100 (CET)
To: Bernardo Cuenca Grau <bcg@cs.man.ac.uk>
Cc: OWL Working Group WG <public-owl-wg@w3.org>
Message-id: <Pine.LNX.4.64.0711290830020.28024@frege.inf.tu-dresden.de>

On Thu, 29 Nov 2007, Bernardo Cuenca Grau wrote:
>>> I have a question, however, concerning the  interaction between range
>>> restrictions and role inclusion axioms. Note that the EL++ version in the
>>> fragments document does impose some restrictions in the use of (complex) role
>>> inclusion axioms, namely the same ones as SROIQ imposes.
>> The document is a bit confusing in that respect stating that "The
>> language EL++, as presented here, is not a fragment of OWL DL, since
>> it provides complex inclusion axioms on Object Properties."
> Well, here I meant that EL++ is not contained in OWL DL, because SHOIN
> does not allow for complex inclusion axioms.
>> , but also
>> "in particular, this document enforces the regularity condition on
>> complex property inclusion axioms required in OWL 1.1. With this
>> restriction, EL++ is a fragment of OWL 1.1."
> What I meant is that the EL++ Tractable Fragments document imposes the
> same regularity condition on the role inclusion axioms as OWL 1.1.
> Therefore, the version of EL++ in this document is not strictly the same
> as the one in your IJCAI-05 paper, which didn't impose regularity
> conditions. Also, I included range restrictions because I thought they
> were harmless, but now I see this has to be checked out. In short, if you
> can check that the role inclusion axioms and the range restrictions do not
> interact badly under regularity conditions, then the document is all
> right. I agree that these statements should be made clearer.

I agree with everything you say.


> Bernardo
>>> My question is
>>> whether these restrictions are not sufficient.  If they do not suffice, I
>>> agree with Carsten in that identifying a variant of EL++ that allows for
>>> domain and range and imposes reasonable constraints in the use of role
>>> inclusion axioms would be  a good thing to have and that version should be
>>> the one included in the document.
>> I suppose that they are sufficient, but I never checked the details.
>> Actually, these restrictions were precisely what I meant in my last
>> mail when talking of a new variant. So there is actually no disagreement
>> here, only somebody has to verify that things remain tractable. I'll
>> try to do that until the Manchester F2F.
>>> I think that the issue whether this fragment which should be called ``OWL
>>> Light" is a much more controversial one. In principle I think there should be
>>> no single ``OWL Light'', but a reasonable menu of choices for such an OWL
>>> Light that each particular user could pick depending on his application
>>> needs.
>> I disagree for the reasons given in my mail(s). Anyway, we should maybe
>> not mix these two issues.
>> greetings,
>>  		Carsten
>> --
>> *      Carsten Lutz, Institut f"ur Theoretische Informatik, TU Dresden       *
>> *     Office phone:++49 351 46339171   mailto:lutz@tcs.inf.tu-dresden.de     *
> ***********************************
> Dr. Bernardo Cuenca Grau
> Research Fellow
> Information Management Group
> School Of Computer Science
> University of Manchester, UK
> http://www.cs.man.ac.uk/~bcg
> ************************************

*      Carsten Lutz, Institut f"ur Theoretische Informatik, TU Dresden       *
*     Office phone:++49 351 46339171   mailto:lutz@tcs.inf.tu-dresden.de     *
Received on Thursday, 29 November 2007 07:30:41 UTC

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