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Re: exchanging OWL through RIF

From: Dave Reynolds <der@hplb.hpl.hp.com>
Date: Fri, 03 Mar 2006 09:54:17 +0000
Message-ID: <44081249.9020909@hplb.hpl.hp.com>
To: edbark@nist.gov
CC: Michael Kifer <kifer@cs.sunysb.edu>, RIF WG <public-rif-wg@w3.org>

Ed Barkmeyer wrote:

> 
> Michael Kifer wrote:
> 
>> I am having a second thought about the requirement that OWL should be
>> exchangeable through RIF by encoding it in FOL (which I am guilty of 
>> voting
>> for also and now attribute it to sleep deprivation :-).
>>
>> I think this requirement is completely misguided.

On the face of it, I agree.

[It was impossible to follow the f2f with it having no phone connection on 
the Tuesday and highly intermittent IRC, so there is a lot of context I'm 
missing here.]

> I think the above statement of the requirement can be misunderstood, but 
> I don't think the intent is at all misguided.
> 
> It is not a matter of "exchanging an OWL ontology"; the requirement is 
> to deliver the semantic content of an OWL ontology as a ruleset, so that 
> a rules engine can incorporate that content into its rulebase.
> 
> A pseudo use-case: A given site "Uhu" using OWL ontologies and an OWL 
> engine may find it necessary to communicate with a site "Rex" that has 
> only "rulesets" and "rule engines" for some task in which Uhu needs the 
> support of Rex.  In this case, it is important that Uhu be able to 
> convert the relevant OWL ontology to a "rules" (RIF) form, so that it 
> can be used by Rex in performing its supporting task.  And the 
> requirement for RIF is that its "FOL subset" be able to capture the 
> semantics of the OWL ontology.
> 
> The alternative view of this scenario is that Uhu simply sends the OWL 
> ontology, and it is incumbent on Rex to convert the OWL ontology to its 
> internal "rules" form.  There is nothing wrong with this view, except 
> that it has no role for RIF -- it makes the OWL->rules conversion a 
> software project for the Rex engine, and another project for the ILOG 
> engine, and another for the Jena engine, etc., creating lots of work for 
> the engine providers and many third parties who are familiar with the 
> proprietary rules forms.  By comparison, any tool that can convert OWL 
> to RIF without loss (standard form to standard form) gives Uhu what is 
> need to work with Rex, and also Rudi and Regina, no matter what rules 
> engines they have.

No I must disagree there.

To take your specific examples, Jena does not implement FOL and I wasn't 
aware that ILOG did.

If the ontology remains in OWL then, for example, a Jena user can continue 
to chose between a rule based approximation to OWL or calling out to a DL 
reasoner. If instead it was given a FOL rule encoding of OWL it would 
either have to reverse engineer the translation ("aha, that looks like the 
output of an OWL translation I can handle that differently") or just have 
to give up ("sorry, I don't do FOL"). I don't see why translating OWL to 
FOL will help Rex for any Rex other than theorem provers (or perhaps 
disjunctive LP engines).

Without context I may be completely missing the point here in which case I 
look forward to seeing the minutes in a form that helps me understand this.

Dave
Received on Friday, 3 March 2006 09:54:37 GMT

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