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Re: OWL1.1 APis

From: Dave Reynolds <der@hplb.hpl.hp.com>
Date: Mon, 11 Dec 2006 10:24:37 +0000
Message-ID: <457D31E5.9030809@hplb.hpl.hp.com>
To: Bijan Parsia <bparsia@cs.man.ac.uk>
CC: public-owl-dev@w3.org

Bijan Parsia wrote:
> On Dec 6, 2006, at 10:52 AM, Dave Reynolds wrote:

>> Had OWL 1.1 had some level of OWL/full compatibility (which I guess 
>> would have required the RDF mapping to directly expose the punning) 
>> then some Jena native reasoning support might have made sense.
>> However, given how big a break OWL 1.1 is from OWL then it's not clear 
>> to me that we can do anything useful on that front in a sufficiently 
>> backward compatible way.
> 
> I'm not sure I understand this line of reasoning. I presume that "Jena 
> native reasoning support" refers to existing rule engines+rulesets 
> bundled with Jena (correct me if I'm wrong, please). 

Correct.

> The *engines* seem 
> to me to be perfectly generic. The rulesets clearly aren't, being built 
> for specific fragments. However, the OWL 1.1 tractable fragments 
> document identifies a *number* of fragments of OWLDL/1.1 which are 
> suitable for impelmentation over a datalog or relational engine (e.g., 
> DLP, EL++, hornSHIQ for datalog, and DL Lite for relational). So, it 
> would be *quite* straightforward to produce additional Jena reasoners 
> which use the underlying rule engines for these fragments. Moreover, it 
> would clearly be possible to extend some of these reasoners to deal with 
> some of the extended features of OWL 1.1 in a "reasonable" manner. 

Oh sure, it would be perfectly possible to identify and implement 
fragments of OWLDL/1.1 reasoning using the same engines. Those would be 
new reasoners, fine. That's not the issue.

The key phrase in the paragraph was "in a sufficiently backward 
compatible way".

What happens when someone applies an existing OWL full reasoner (the 
Jena reasoners are all tiny fragments of OWL/full) to an OWLDL/1.1 
document? It seems to me that would be unsound, any use of punning in 
the OWLDL/1.1 document would lead to incorrect entailments.

Up till now the semantic web stack has nested nicely. If I apply an RDFS 
reasoner to an OWL document (whether DL or full) all the deductions are 
sound. If I apply an OWL/full reasoner to an OWL/DL document the results 
are sound. It seems to me that OWL/DL1.1 breaks this nesting, if I apply 
an OWL-(full)-as-currently-specified reasoner to an OWLDL/1.1 document 
the results are not sound.

Is that right or am I missing something here?

This seems to mean that a pile of triples pulled from an OWLDL/1.1 
document must be treated differently from an identical looking pile of 
triples pulled from an OWL (as in the current specs) document. Which 
requires a little thought on the part of people with RDF APIs.

> (Interest has already been expressed in extending the OWL Full semantics 
> to deal some of these features; assuming that this happens, "reasonable" 
> could be interpreted as "consistent with the semantics".)

Interesting though most of the extended features, like qualified 
cardinality restrictions, don't seem likely to cause problems.

Dave
Received on Monday, 11 December 2006 10:25:02 GMT

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