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Re: Fragments discussion, continued

From: Jim Hendler <hendler@cs.rpi.edu>
Date: Thu, 21 Feb 2008 11:45:35 -0500
Cc: Boris Motik <boris.motik@comlab.ox.ac.uk>, "'Web Ontology Language ((OWL)) Working Group WG'" <public-owl-wg@w3.org>
Message-Id: <35DF02BD-080B-4985-B084-D4F4F41F87B5@cs.rpi.edu>
To: Alan Ruttenberg <alanruttenberg@gmail.com>

On Feb 21, 2008, at 10:35 AM, Alan Ruttenberg wrote:

> On Feb 21, 2008, at 10:07 AM, Jim Hendler wrote:
>
>> Alan, can you explain who it is whose been asking for that fragment  
>> (as separate from the Prime fragment) and what the distinguishing  
>> property would be?
>
> Hello Jim,
>
> First, OWL Lite is not proposed as a Rec track fragment, so it isn't  
> properly in this list. My proposal was to have that be a note, as an  
> accommodation to existing users.

Whatever we decide on that, I was just talking about the effort - the  
key is I think we have consensus about doing minimal work on  
maintaining Lite - so I don't see this as an argument point.

>
> Regarding DL-Lite, I'm not sure I have more to add to what I've  
> already said.
>
>> 3) A fragment characterized by scalability to large numbers of  
>> instances (not necessarily scalable tbox) , but with strong  
>> guarantees with respect to completeness and consistency detection.
> ..
>> Such a fragment  fills a hole that neither of two other fragments  
>> fill, as It is likely that OWL Prime will not allow existentials  
>> in  a rule head (following pD*), and EL++ is not as scalable.
>
>> In addition DL-Lite is implementable in relational databases with  
>> queries translatable to SQL. I have heard of two academic  
>> implementations ("the italians" &  Jeff Pan) and a commercial  
>> implementation - Clark and Parsia's, and the nature of the fragment  
>> is such that it would be easily adoptable by relational database  
>> providers.
>
>> Finally, it is my judgement, as a user, that strong guarantees of  
>> the ability to detect inconsistency and give complete answers bring  
>> high value to science applications.
>
> Note that these criteria have not been suggested as those that guide  
> the design of OWL Prime. Should they turn out to be achievable, and  
> there are implementations that show this, then I would, of course,  
> reconsider, as I am more interested in the criteria than the  
> fragment. DL-Lite is already sitting in this space with 3  
> independent implementations, so I naturally suggested it.
>
> FWIW, I will be a customer for a fragment like (3) in parts of my  
> work, but to be honest, I see all three as being tools that I could  
> put to good use.
>
> In my view, the argument for moving from 3 to 2 rec track fragments  
> is not compelling, and will meet with resistance for  small gain. In  
> the spirit of compromise, and in the interest of moving forward, I  
> would prefer if we now focus on the work of answering the remaining  
> questions we need to in order to sanity check and ensure ourselves  
> that these fragments pass muster.  Of the 3 rec track fragments,  
> there were significant and substantive questions about the details  
> about the details OWL Prime, and DL-Lite. For OWL-Lite, we have some  
> verification of the conditions that we set out.
>

Sorry Alan, I've read the above, but I'm afraid I still don't get it.   
All of the fragments in the fragments documents have implementations  
and some users.  Carsten's suggestion was that we use some criteria  
including user demand for which fragments we move to rec track, and it  
seemed people were generally in agreement with that.  For Owl Prime we  
had Oracle and HP saying their users want it and explaining why--  
those are "real people" in real numbers - so I think it makes sense.   
For EL++, Carsten argued that for most of the people doing large Tbox  
ontologies this was a useful fragment - more importantly, he offered  
several real examples and it was also pointed out that there also  
seems to be some govt support behind that (according to people on a  
previous telecon) - so those have both been motivated.  You've  
suggested another fragment move Rec track, and all I'm asking is  
whether you can motivate it on the same dimensions that the others were.
  -JH
p.s. Maybe my asking you for performance and users is as meaningless  
as you asking me about completeness (See the other thread), but if  
we're trying to convince industry to move in certain directions, it is  
important to help document why they should...
Received on Thursday, 21 February 2008 16:46:15 GMT

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