Re: Undiscussed DL-Lite Changes: SameIndividuals out, UNA + Functional Properties in

DL-Lite doesn't have UNA as such -- but the definition says that to  
be in the DL-Lite fragment an ontology must include  
DifferentIndividual statements for all individuals in the ontology.  
This means that the fragment is still a fragment (every DL-Lite  
ontology is a DL ontology and has exactly the same semantics in DL).  
The DifferentIndividual statements effectively *assert* UNA. This is  
needed if the OWL DL-Lite profile is to enjoy the computational  
properties that are its "Raison d'etre" (because the profile also  
includes functional roles). Having same individual statements in DL- 
Lite would thus be rather pointless, as asserting SameIndividualAs  
for any two non-equal individuals would result in ontology  

Regarding easy keys, it isn't quite true to say that they "don't do  
anything". In the presence of (asserted) UNA they behave rather like  
database constraints -- two individuals having the same key is a  
constraint violation and would again lead to an inconsistency.


On 7 Jul 2008, at 18:05, Michael Smith wrote:

> In the last telecon, during discussion of easy keys [1], it was stated
> that UNA applied to the DL-Lite profile, which I questioned.  This was
> not the case at F2F2, so I referenced the document history.
> In a series of edits to the profile doc on 2008-05-14, SameIndividual
> axioms were removed from the DL-Lite profile, and the UNA was added
> along with functional property axioms.  I'd like these changes to be
> discussed by the WG, perhaps with comment on why they were initially
> made without discussion.
> My opinion -- influenced largely by discussions at F2F2 -- is that (1)
> SameIndividual axioms are a more desirable feature than functional
> properties and (2) a profile of OWL with the UNA is problematic.
> This conversation is relevant now because (I believe) the  
> applicability
> of easy keys to DL-Lite is dependent on the UNA.
> Thanks,
> -- 
> Mike Smith
> Clark & Parsia
> [1] 
> 2008-07-02#action_165_Investigate_easy_keys_in_DL__2d_Lite___2f___20_D 
> iego_Calvenese

Received on Thursday, 10 July 2008 14:01:34 UTC