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Re: private review of Profiles, Section 4.3 (OWL 2 RL/RDF rules)

From: Ivan Herman <ivan@w3.org>
Date: Sat, 18 Apr 2009 10:22:24 +0200
Message-ID: <49E98DC0.3080904@w3.org>
To: Michael Schneider <schneid@fzi.de>
CC: Boris Motik <boris.motik@comlab.ox.ac.uk>, OWL 2 <public-owl-wg@w3.org>


Michael Schneider wrote:

[snip]
>> xsd:nonNegativeInteger.
>> I see that this might be misunderstood; however, I don't believe that we
>> have a
>> problem formally speaking. We say that the rules are a bunch of
>> universally
>> quantified clauses, right? Now it all depends on how you interpret the
>> literals
>> in there. I believe these should be interpreted *semantically*. That is,
>> "0"^^xsd:nonNegativeInteger should be interpreted as the integer zero,
>> just like
>> "0"^^xsd:integer. Thus, if your data contains the latter but the rule
>> contains
>> the former, the rule still applies because the two values are
>> semantically
>> equivalent.
>>
>> I haven't changed anything to this end.
> 
> I'm fine with this. However, I think that we should have a word on this 
> in the document, or I believe it will become a FAQ, in particular for 
> implementers. (I wonder how Ivan treats cardinality restrictions in his
> implementation at the moment :-)) But this can be deferred for the 
> moment, since it is purely editorial.
> 

I (instinctively:-) did more or less what Boris said. I take the literal
and I see if it can be interpreted as a value '1' or '0'. If so, I
follow the rule, if not, the rule is ignored.

[snip]
> Ah, I see, I missed the point that ExactCardinality is not in the fragment.
> 
> Just a point of clarification: I was only proposing to exactly 
> mirror the set of "max" rules. So in the case of exact-1, this 
> would have meant that there would have only been rules of the 
> kind "if there are two triples s p o1 and s p o2, then o1 = o2". 
> I did not ask for rules that introduces bNodes. But this 
> discussion is moot now, given your argument above.
> 

I think it is better not to have this. If I look at (exact) cardinality
than I would expect something that is not only the 'max' rule. In this
sense _not_ having it among the rules may be cleaner, so to say.

Cheers

Ivan


> Cheers and thanks,
> Michael
> 
> --
> Dipl.-Inform. Michael Schneider
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-- 

Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
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Received on Saturday, 18 April 2009 08:23:02 GMT

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