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

From: Ivan Herman <ivan@w3.org>
Date: Fri, 07 Mar 2008 09:26:03 +0100
Message-ID: <47D0FC1B.1060708@w3.org>
To: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>
CC: Jim Hendler <hendler@cs.rpi.edu>, Bijan Parsia <bparsia@cs.man.ac.uk>, "Web Ontology Language ((OWL)) Working Group WG" <public-owl-wg@w3.org>
Can we envisage (not necessarily for this draft, of course) to add an 
informative annex to describe this mapping to SQL explicitly (just as we 
have a rule set for OWL-R)? I think this would have a huge impact.

Ivan

Ian Horrocks wrote:
> 
> Actually, the primary idea of DL-Lite is that it has logspace data 
> complexity, which means that query answering can be implemented using 
> standard (relational) DB technology. In particular, a conjunctive query 
> against a DL-Lite ontology can be re-written as an SQL query against a 
> relational DB containing instance data.
> 
> Ian
> 
> 
> On 6 Mar 2008, at 19:23, Jim Hendler wrote:
> 
>>
>> I thought the primary idea of DL-Lite was that it would provide 
>> primary database functionality -- how can it do that without keys?
>>
>>
>> On Mar 6, 2008, at 6:18 AM, 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.
>>>
>>> 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.
>>>
>>>
>>>
>>
>> "If we knew what we were doing, it wouldn't be called research, would 
>> it?." - Albert Einstein
>>
>> Prof James Hendler                http://www.cs.rpi.edu/~hendler
>> Tetherless World Constellation Chair
>> Computer Science Dept
>> Rensselaer Polytechnic Institute, Troy NY 12180
>>
>>
>>
>>
>>
> 
> 

-- 

Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf


Received on Friday, 7 March 2008 08:26:15 GMT

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