Re: ISSUE-77 (Horn-SHIQ): Extending Horn-SHIQ

On Mittwoch, 28. November 2007, OWL Working Group Issue Tracker wrote:
> ISSUE-77 (Horn-SHIQ): Extending Horn-SHIQ
>
> http://www.w3.org/2007/OWL/tracker/issues/
>
> Raised by: Bijan Parsia
> On product:
>
> (On behalf of Carsten Lutz.)
>
> Why Horn-SHIQ, and not Horn-SHIQO, i.e., why not include nominals?  I
> know that nothing has been published on Horn-SHIQO, but the difference
> to Horn-SHIQ is not so big, and we have enough (wo)man-power and
> expertise in this group to check whether something breaks
> w.r.t. Hornness and other desirable properties (it shouldn't!).

Yes, this would be useful and also doable. Let me point out that we have 
already investigated some formal properties of DLs that are Horn while also 
having nominals or other OWL1.1 features, in particular of

* Horn-FL0 & Horn-FLOH [1] (which also gives a definition of Horn-SHOIQ),
* ELRO [2] (this is more in line with the EL discussion, but still a fragment 
of "Horn-OWL1.1").

(Note: most of these are "academic fragments" outside 
the "which-fragments-discussion" -- don't be alarmed by even more acronyms ;)

Markus

[1] M. Krötzsch, S. Rudolph, P. Hitzler: Complexity Boundaries for Horn 
Description Logics. AAAI 2007. 
http://korrekt.org/index.php/Complexity_Boundaries_for_Horn_Description_Logics
[2] M. Krötzsch, S. Rudolph, P. Hitzler: Conjunctive Queries for a Tractable 
Fragment of OWL1.1. ISWC 2007. 
http://korrekt.org/index.php/Conjunctive_Queries_for_a_Tractable_Fragment_of_OWL1.1

>
> This remark does not only apply to Horn-SHIQ and not only to nominals:
>
> - what other things that are in OWL 1.1 but not in Horn-SHIQ could be
>   added to Horn-SHIQ without loosing nice properties?
>
> - In general: shouldn't we try to have the tractable fragments "up to
>   date" with main OWL 1.1? For the case of EL++, I will report on this
>   in a later mail.


-- 
Markus Krötzsch
Institut AIFB, Universät Karlsruhe (TH), 76128 Karlsruhe
phone +49 (0)721 608 7362        fax +49 (0)721 608 5998
mak@aifb.uni-karlsruhe.de        www  http://korrekt.org