Re: comment on the fragment document: (inverse) functional and DL-Lite

Bijan Parsia wrote:
> 
> On 6 Mar 2008, at 11:04, Ivan Herman wrote:
> 
>> Boris, Bernardo,
>>
>> I went through
>>
>> http://www.w3.org/2007/OWL/wiki/Fragments_Proposal
>>
>> again today. One thing that I may have missed: I tried to see if I can 
>> use (inverse)functional properties for DL-Lite or not. I did not find 
>> any reference to those neither in 3.1 nor in 3.2. Again, I may have 
>> missed something...
> 
> Let's see if I can discern from the text the situation. (As a test of 
> the spec.)
> 
> In section 3:
>     http://www.w3.org/2007/OWL/wiki/Fragments_Proposal#DL-Lite
> 
>     """Several variants of DL-Lite have been described in the 
> literature. The variant presented here is called DL-LiteR since it 
> allows for property inclusion axioms; it therefore contains the 
> intersection between RDFS and OWL 1.1 DL. Other variants trade property 
> inclusion axioms for functionality and inverse-functionality of object 
> properties."""
> 
> I think this is clear that functionality and inverse functionality of 
> *object* properties are forbidden.
> 

Hm. Yes, in a convoluted manner it does say that, indeed.... And, in 
fact, the fact that it is *not* listed in 3.2.2. actually reinforces 
that. This is true, my apologies.

But then it becomes an editorial issue; indeed, the list headed by:

"The following features of OWL 1.1 are missing in DL-Lite:"

does not refer to the (inverse)functional properties and, I must admit, 
that is where I tried to find a reference to it

Ivan


> Actually ,the rest of the sections are quiet about data properties 
> altogether. Which would mean that data properties are forbidden in this 
> variant. Which means that it's not really the intersection of RDFS and 
> OWL 1.1 DL?
> 
> I do think that if we make this DL Lite not have data properties, the 
> text should call that out (e.g., in the list of missing features). OTOH, 
> I think we should allow data properties ;) I would think it would be ok 
> to trade datasubproperties for keys (from a user pov)...I don't know if 
> that would be ok from the logic/impelmentation pov off the top of my had 
> (while retaining object subproperties).
> 
> Cheers,
> Bijan.
> 
> 
> 

-- 

Ivan Herman, W3C Semantic Web Activity Lead
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