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Re: Negative object/data property assertions in EL++

From: Achille Fokoue <achille@us.ibm.com>
Date: Wed, 26 Mar 2008 19:38:23 -0400
To: "Web Ontology Language ((OWL)) Working Group WG" <public-owl-wg@w3.org>, Carsten Lutz <clu@tcs.inf.tu-dresden.de>
Cc: Evren Sirin <evren@clarkparsia.com>
Message-ID: <OFA78E8B88.43715F8A-ON85257418.007FEF82-85257418.0081DB7B@us.ibm.com>

I have already addressed Evren's comment.  As to nonstructural 
constraints, at the beginning of  section 3.2, it is stated that "all the 
nonstructural restrictions on axioms are exactly as in Section 10 of the 
structural specification [OWL 1.1 Specification]", which, I think, is 
sufficient if range is not supported (as in the EL++ paper referenced  in 
the fragments document).  Last week, I added a comment about this issue in 
my review. If we are to include range in EL++, at the very least we need a 
reference to a paper describing how EL++ is extended with range.  My 
understanding is that you have submitted such  a paper at OWLED. Could you 
please make it available on the wiki?


public-owl-wg-request@w3.org wrote on 03/26/2008 07:12:42 PM:

> On Wed, 26 Mar 2008, Evren Sirin wrote:
> >
> > I see that negative object/data property assertions are explicitly
> disallowed 
> > in the EL++ fragment. But one can express
> >
> > NegativeObjectPropertyAssertion(p a b)
> >
> > as
> >
> > DisjointClasses(ObjectOneOf(a) ObjectHasValue(p b))
> >
> > which is allowed in EL++. Same is possible for data property 
> assertions using 
> > DataHasValue restriction. So I'm wondering if disallowing 
> > assertions in EL++ is necessary.
> I agree with what you say and don't think that negative property 
> should be disallowed. Actually, this is one of the differences between 
> Wiki page on EL++ at http://www.w3.org/2007/OWL/wiki/EL and the official 

> fragments document. Another notable one is that the non-structural 
> restrictions have been completely omitted, which actually means that the
> version of EL++ described in the fragments document is not tractable.
> Are these just editing mistakes or is there some other reason?
> greetings,
>        Carsten
> --
> *      Carsten Lutz, Institut f"ur Theoretische Informatik, TU Dresden   
> *     Office phone:++49 351 46339171   mailto:lutz@tcs.inf.tu-dresden.de 
Received on Wednesday, 26 March 2008 23:39:02 UTC

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