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Re: ISSUE-80 (DL-Lite): REPORTED: DL-Lite

From: Bernardo Cuenca Grau <bcg@cs.man.ac.uk>
Date: Wed, 28 Nov 2007 17:57:34 +0000
Message-ID: <474DAC0E.7060301@cs.man.ac.uk>
To: OWL Working Group WG <public-owl-wg@w3.org>

Ok. I see quite a lot of discussion concerning the tractable fragments 
document, and I will try to reply to all the issues.

The selected version of DL-Lite is DL-Lite_R. As Carsten points out, 
there are other variants of DL-Lite for which reasoning is tractable. 
These variants share a common core, but provide different extensions to 
this core corresponding to different choices that one has to make in 
order to keep tractability. For example, DL-Lite_R extendes the ``core'' 
of the language with role inclusion axioms. DL-Lite_F extends it with 
role functionality of roles and their inverses. If both role 
functionality and role inclusion axioms were to be included, the nice 
computational properties of the DL-Lite family of languages would be 

The selection of DL-Lite_R was motivated by the fact that it is a proper 
extension of the DL subset of RDF-Schema, which provides role-inclusion 
axioms but not functionality, and therefore DL-Lite_R is a language that 
lies in between such DL subset of RDF-Schema and OWL Lite.

In any case, I agree that these choices should be discussed and that we 
could do a better job in presenting all (or most of) the variants. Also, 
as Carsten points out, there is also a distinction between tractability 
of reasoning and the fact that query answering can be handled using 
RDBMS, and this should probably be made explicit if we are to present 
other variants of DL-Lite.

I think we should discuss the alternatives within the WG


OWL Working Group Issue Tracker wrote:
> ISSUE-80 (DL-Lite): REPORTED: DL-Lite
> http://www.w3.org/2007/OWL/tracker/issues/
> Raised by: Bijan Parsia
> On product: 
> (On behalf of Carsten Lutz.)
> There are many versions of DL-Lite around, all of them tractable,
> and many (but not all) of them reducible to query answering in
> RDBMS. I wonder how the fragment of DL-Lite was selected that is
> currently in the document and what are the alternatives? Maybe
> Bernardo can comment on this.
Received on Wednesday, 28 November 2007 18:02:46 UTC

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