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

From: Carsten Lutz <clu@tcs.inf.tu-dresden.de>
Date: Wed, 28 Nov 2007 22:13:05 +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.4.64.0711282209070.27817@frege.inf.tu-dresden.de>

On Wed, 28 Nov 2007, Bernardo Cuenca Grau wrote:
> 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 compromised.

Yes, but in their OWLED06 paper, the romans show how these problems
are avoided when DL-Lite_R and DL-Lite_F are merged in a more careful
way (don't ask me for details, though :).  And then, there are other
versions such as DL-Lite Horn and DL-Lite Krom proposed by Alessandro,
Diego, and Misha. Also tractable (and you may ask for details :).

> 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

I have a different opinion. If we try to present all variants of all
fragments, we are lost and we will have an endless (and confusing)
list of fragments. Moreover, we are bound to be outdated extremely
quickly. I believe that we should make clever choices, instead of
being exhaustive.


*      Carsten Lutz, Institut f"ur Theoretische Informatik, TU Dresden       *
*     Office phone:++49 351 46339171   mailto:lutz@tcs.inf.tu-dresden.de     *
Received on Wednesday, 28 November 2007 21:13:19 UTC

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