Re: ISSUE-3: REPORTED: Lack of anonymous individuals

Carsten Lutz <clu@tcs.inf.tu-dresden.de> said:

> 
> On Thu, 8 Nov 2007, gstoil@image.ece.ntua.gr wrote:
> >
> > Carsten Lutz <clu@tcs.inf.tu-dresden.de> said:
> >
> >>
> >> On Thu, 8 Nov 2007, gstoil@image.ece.ntua.gr wrote:
> >>>
> >>> Carsten Lutz <clu@tcs.inf.tu-dresden.de> said:
> >>>
> >>>> relation. Actually, we could think of adding the universal property
> >>>> and interpreting the anonymous individuals as skolem constants, as you
> >>>> propose. This means that, if really needed, true anonymous individuals
> >>>> can still be recovered via the universal property. The restriction to
> >>>> tree-shaped interconnections is then automatic. And we don't introduce
> >>>> conjunctive queries to ontology entailment.
> >>>>
> >>>> greetings,
> >>>>
> >>>>  	Carsten
> >>>
> >>> But is there currently any reasoning support for the universal role in
SROIQ?
> >>> I believe there isn't any.
> >>
> >> Yes, it is in SROIQ. But even if it wasn't: it's useful, it's easily added
> >> to tableau algorithm, and it shouldn't be difficult to implement.
> >>
> >> greetings,
> >>  		Carsten
> >>
> >
> > But from the paper of SROIQ I am reading the following:
> 
> That's just what I wrote: disallow it in...
> 
> > Def 2: "A RIA ... not including the universal role"
> 
> ...role inclusions
> 
> > Def 3: "For roles R,S != U..."
> 
> ...role property assertions (because the properties of the universal
> role are fixed)
> 
> > Def 15: "...let C_o be a SROIQ-concept not using the universal role..."
> 
> ...number restrictions (because you would have to do finite model reasoning
> if you allowed that).
> 
> But *do* allow it in existential and universal restrictions.

Sorry but I don't see where the definition differentiates between
SROIQ-QCR-concepts and SROIQ-valua/existential-concepts. 

For example, I don't see how the current algorithm could classify 
{a:\not \exists uprop.Self} as inconsistent.

Greetings,
-gstoil

> 
> 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 Thursday, 8 November 2007 14:09:23 UTC