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Re: draft response for LC comment 32 CO1

From: Ivan Herman <ivan@w3.org>
Date: Fri, 20 Feb 2009 11:32:42 +0100
Message-ID: <499E86CA.6030508@w3.org>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
CC: public-owl-wg@w3.org
Thanks!

Ivan

Peter F. Patel-Schneider wrote:
> From: Ivan Herman <ivan@w3.org>
> Subject: Re: draft response for LC comment 32 CO1
> Date: Fri, 20 Feb 2009 09:33:06 +0100
> 
>> Well... although what you say is technically true, I would not find it
>> unreasonable if some characteristic _examples_ would be added to the
>> profile document for both cases that Chime refers to. This tough
>> rebuttal is a little bit to brisk for my taste, and we should have some
>> more explanation in our documents in my view. (Whether this is in the
>> profile or somewhere else like the primer is of course a different issue!)
>>
>> I just came up with some things that we could add:
>>
>> - For his first comment, we could, eg, refer to the fact that arbitrary
>> RDF graphs may include statements on the otherwise reserved vocabulary
>> with all kinds of funny consequences, or that they would allow defining
>> functional datatype properties whose consequences are a bit unpredictable.
> 
> Fine.  I'll put in something like:
> 
> Arbitrary RDF graphs can include constructs that have surprising
> consequences.  The reasons for these are many and varied, including
> effects on the "syntax" of OWL 2.  Because there are so many ways in
> which the rules could incorrect, the working group has decided not to
> exactly characterize how the incorrectness arises, but instead has
> included a mention that arbitrary RDF graphs can affect the
> underpinnings of OWL, as follows:
> 
>   For ontologies satisfying the syntactic constraints described in
>   Section 4.2, a suitable rule-based implementation will have desirable
>   computational properties; for example, it can return all and only the
>   correct answers to certain kinds of query (see Section 4.3 and
>   [Conformance]). Such an implementation can also be used with arbitrary
>   RDF graphs. In this case, however, these properties no longer hold —
>   in particular, it is no longer possible to guarantee that all correct
>   answers can be returned*, for example if the RDF graph uses the
>   built-in vocabulary in unusual ways.*
> 
>> - An example of the (missing) consequences due to the missing RDF(S)
>> axiomatic triples and some of the entailement rules is that
>>
>> rdf:_i rdf:type rdfs:ContainerMembershipProperty . (axiomatic rule)
>> meaning that
>> rdf:_i rdfs:subPropertyOf rdfs:member . (rdfs12 entailement rule)
>>
>> If these were around, an OWL RL user could handle container membership
>> more easily with those rules.
> 
> I don't know whether *these* triples and rules provide an example of the
> missing inferences.  Perhaps Boris can comment or provide an example.
> 
>> Ivan
> 
> peter
> 
> 
>> Peter F. Patel-Schneider wrote:
>>> [Draft Response for LC Comment 32:] CO1
>>>
>>> Dear Chimezie,
>>>
>>> Thank you for your message
>>>   http://lists.w3.org/Archives/Public/public-owl-comments/2009Jan/0039.html
>>> on the OWL 2 Web Ontology Language last call drafts.  
>>>
>>> Arbitrary RDF graphs can include constructs that have surprising
>>> consequences.  The reasons for these are many and varied, including
>>> effects on the "syntax" of OWL 2.  Because there are so many ways in
>>> which the rules could incorrect, the working group has decided not to be
>>> more explicit in the introduction to OWL 2 RL.
>>>
>>> There are an infinite number of RDFS axiomatic triples, so including
>>> them all in the OWL 2 RL rules does not directly lead to an effective
>>> rule implementation.  There are some RDFS rules that produce
>>> consequences that are not relevant to the conclusions guaranteed by
>>> Theorem PR1.  Listing all the "deficiencies" is not particularly easy,
>>> and would probably only confuse the issue.  The working group has
>>> therefore decided not to be more explicit in the preamble to Theorem
>>> PR1.
>>>
>>> Please acknowledge receipt of this email to
>>> <mailto:public-owl-comments@w3.org> (replying to this email should
>>> suffice). In your acknowledgment please let us know whether or not you
>>> are satisfied with the working group's response to your comment. 
>>>
>>> Regards,
>>> Peter F. Patel-Schneider
>>> on behalf of the W3C OWL Working Group 
>>>
>>> No trees are known to have been harmed in the preparation of this
>>> response.
>>>
>> -- 
>>
>> Ivan Herman, W3C Semantic Web Activity Lead
>> Home: http://www.w3.org/People/Ivan/
>> mobile: +31-641044153
>> PGP Key: http://www.ivan-herman.net/pgpkey.html
>> FOAF: http://www.ivan-herman.net/foaf.rdf

-- 

Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf



Received on Friday, 20 February 2009 10:33:20 GMT

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