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

From: Carsten Lutz <clu@tcs.inf.tu-dresden.de>
Date: Thu, 27 Mar 2008 00:12:42 +0100 (CET)
To: Evren Sirin <evren@clarkparsia.com>
Cc: "Web Ontology Language ((OWL)) Working Group WG" <public-owl-wg@w3.org>
Message-id: <Pine.LNX.4.64.0803270005170.23218@frege.inf.tu-dresden.de>

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 negative property 
> assertions in EL++ is necessary.

I agree with what you say and don't think that negative property assertions
should be disallowed. Actually, this is one of the differences between my 
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 23:13:31 GMT

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