Re: A possible way of going forward with OWL-R unification (ISSUE-131)

Michael,

on another 'branch' of this discussion, Boris and I seem to converge 
towards a solution:

HTTP://www.w3.org/mid/487B16F4.7070709@w3.org

by having a clear name for the rule based solution, although we might 
have to make a clear difference between 'syntactic' profiles (eg, 
OWL-R-DL, in today's terminology) and 'implementation' profiles (eg, 
OWL-R-Full or what Boris calls OWL-R/RDF). The only additional problem I 
see in your mail is the strong reference to RDFS, which actually refers 
to ISSUE-116:

http://www.w3.org/2007/OWL/tracker/issues/116

Is that correct? And true, this is actually an issue that we will have 
to solve. Or do you see other issues as well?

Ivan

Michael Schneider wrote:
> Zhe Wu wrote:
> 
>> For the record, I am happy with the way OWL-R is written. Like I said in
>> the conference call, I haven't heard any
>> complaints about it myself. Frankly, the rule set in OWL R Full is what
>> I care the most.
>> I will be happy if Boris's proposal is accepted, as long as we clearly
>> point out that the rules can be applied to any
>> RDF graphs. The OWL-R unification idea can reduce a bit confusion. I
>> don't consider it a must-have though.
>>
>> In short, I don't have strong opinions either way.
>>
>> Thanks,
>>
>> Zhe
> 
> Here is my opinion.
> 
> For me, a crucial point is whether OWL-R, when applied in the "relaxed mode", 
> i.e. as a triple rule language on arbitrary RDF graphs, will produce *every* 
> RDFS entailment.
> 
> If OWL-R/relaxed turns out to not be a proper RDFS extension (an "enhanced 
> RDFS", "RDFS plus a bit", "RDFS 3.0", or whatever you like to call it), then I 
> would regard OWL-R to be pretty pointless from an RDF community point of view. 
> It would probably be hard to explain to RDF people, why particular 
> RDFS-features are missing, while others are supported. It would certainly give 
> to RDF people a warmer feeling to learn that an OWL-R reasoner will produce 
> all the results of an RDFS reasoner, if applied to RDF graphs, which don't 
> contain any of the additional OWL vocabulary.
> 
> Also, having OWL R as an RDFS-extension would probably ease the production of 
> prototypical implementations for OWL R. For example, in order to create an OWL 
> R Full reasoner, as defined at the moment, it is as simple as taking Jena's 
> RDFS reasoner, and adding the additional rules as given by the OWL R Full 
> spec. That is a matter of a few hours, I suppose.
> 
> However, I do *not* believe that OWL R is rejected by the RDF community, if 
> OWL R does not extend RDFS. I would rather expect that in such a case RDF 
> people will just start to create such RDFS-extending implementations of OWL 
> R -- simply because it's easier and more straightforward for them to do so. 
> But then, we would be in the undesirable situation that the "typical" OWL R 
> implementation would not conform to the W3C spec. In fact, such 
> implementations would be OWL-R *non-sound*, since they would produce 
> additional inferences, which are not entailments in the official OWL R/relaxed 
> language.
> 
> So in order to be allowed to put the "W3C OWL-R" brand on their product, 
> implementers would need to create an additional "strict OWL/R mode" of their 
> reasoner. This would demand additional effort for something, which is unlikely 
> to be applied by many people, simply because the RDFS-extending OWL-R 
> implementation is more capable than the official one. On the other hand, it is 
> even more unlikely that implementers will /exclusively/ produce "strict mode" 
> versions, because then they would be in a disadvantage compared to their 
> competitors.
> 
> In such a situation, I wouldn't be much surprised if RDF people (both 
> implementers and users) soon start to claim that the W3C OWL-R spec is broken. 
> :(
> 
> Best regards,
> Michael
> 

-- 

Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
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