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

From: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>
Date: Thu, 6 Mar 2008 23:26:38 +0000
Message-Id: <05AB7E97-A413-49F1-8AF9-907ED221FFE8@comlab.ox.ac.uk>
Cc: Bijan Parsia <bparsia@cs.man.ac.uk>, "Web Ontology Language ((OWL)) Working Group WG" <public-owl-wg@w3.org>
To: Jim Hendler <hendler@cs.rpi.edu>

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
>
>
>
>
>
Received on Thursday, 6 March 2008 23:26:50 GMT

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