Re: Question about the topProperty

On Freitag, 25. April 2008, Carsten Lutz wrote:
> On Thu, 24 Apr 2008, Michael Schneider wrote:
> > Hi!
> >
> > I have a question regarding the topProperty and the bottomProperty. If
> > these properties are going to be introduced into OWL 2, would they only
> > go into OWL-DL/Full, or can they also be included into each of the
> > profiles? Do these properties add to the semantic expressivity or to the
> > computational complexity of the profiles?
>
> For the case of EL++: the top and bottom properties can be included. They
> do add to the expressivity, but do not increase computational complexity.
> The latter is very easy to see by looking at existing EL++ algorithms,
> and I think it also follows from Markus' rule-extension of EL++.

Yes, and this is still the case if you add things like role disjointness and 
local reflexivity. If you add only universal properties, it is indeed very 
easy to modify the existing algorithms.

Anything above OWL DL can easily axiomatise a top property (using DL 
pseudo-notation here, sorry):

TOP SUBCLASSOF EXISTS R1.{a}
TOP SUBCLASSOF EXISTS R2.{a}
R1 o R2 SUBPROPOF U

Then U is the universal. In other words: when you have defined your semantics 
for TOP (thing), you also can define an according "cross product" TOP x TOP 
easily. BottomProperties are even easier (see previous telco logs).

Cheers,

Markus

>
> greetings,
>  		Carsten
>
> --
> *      Carsten Lutz, Institut f"ur Theoretische Informatik, TU Dresden     
>  * *     Office phone:++49 351 46339171   mailto:lutz@tcs.inf.tu-dresden.de
>     *



-- 
Markus Krötzsch
Institut AIFB, Universität 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