Re: Draft second response for LC Comment 51a RM1-2

Works for me.

peter


From: Ivan Herman <ivan@w3.org>
Subject: Re: Draft second response for LC Comment 51a RM1-2
Date: Fri, 13 Mar 2009 10:55:55 +0100

> I am not sure it is wise to refer to a formal objection (although this
> is procedurally correct). Let us not ask for extra formal trouble:-) I
> would also not open the door on possible changes after CR in this
> respect; afaik, this feature was implemented in OWL 1 already, this is
> not a feature that OWL 2 introduced as new (unless I miss something
> fundamental here).
> 
> He also refers to the argument on backward compatibility with OWL 1 as
> putting our head in the sand which is not as simple as he says per the
> charter of this group.
> 
> Ie, I shortened the answer that way:
> 
> [[[
> The Working Group acknowledges that multi-valued data properties
> together with datatype facets do pose an implementation burden. However,
> the group is not chartered[1] to do any changes that would break the
> backward compatibility with OWL 1, which had numerous implementations
> with non-functional datatypes, as well as deployment of ontologies
> possibly relying on that feature. Note also that no erratum was reported
> on this feature on OWL 1[2]. Therefore, the Working Group does not
> intend to change OWL 2 in this way.
> 
> Regards,
> Peter F. Patel-Schneider
> on behalf of the W3C OWL Working Group
> 
> [1] http://www.w3.org/2007/06/OWLCharter.html
> [2] http://www.w3.org/2001/sw/WebOnt/errata
> 
> ]]]
> 
> How does that sound?
> 
> Ivan
> 
> Peter F. Patel-Schneider wrote:
>> [Draft second response for LC Comment 51a RM1-2]
>> 
>> To: Ralf Moeller <r.f.moeller@tu-harburg.de>
>> Subject: [LC Response] To Ralf Moeller Re: OWL2
>> 
>> Dear Ralf:
>> 
>> This message is in reply to your comment available as
>> <http://lists.w3.org/Archives/Public/public-owl-comments/2009Jan/0059.html>,
>> on the OWL 2 Web Ontology Language last call drafts; the initial
>> response from the working group
>> <http://lists.w3.org/Archives/Public/public-owl-comments/2009Feb/0031.html>;
>> and your subsequent reply, available as
>> <http://lists.w3.org/Archives/Public/public-owl-comments/2009Mar/0018.html>
>> 
>> 
>> The Working Group acknowledges that multi-valued data properties
>> together with datatype facets do pose an implementation burden.
>> However, the Working Group feels that multi-valued data properties are
>> the correct way to go in OWL 2.
>> 
>> Therefore, the Working Group does not intend to change OWL 2 in this
>> way, at least for now.  If implementation experience shows that this
>> part of OWL 2 is too difficult to implement the Working Group will, of
>> necessity, revisit this decision.
>> 
>> 
>> You may, if you wish, press this matter further by filing a formal
>> objection to this aspect of OWL 2, using standard W3C procedures.
>> 
>> Regards,
>> Peter F. Patel-Schneider
>> on behalf of the W3C OWL Working Group
>> 
>> 
>> == Past Messages ==
>> 
>> 
>> From: Ralf Moeller [mailto:r.f.moeller@tu-harburg.de]
>> Sent: Friday, March 06, 2009 1:45 PM
>> To: Michael Schneider
>> Subject: Re: [LC Response] To Ralf Moeller Re: OWL2
>> 
>> Dear Michael,
>> 
>> I would like to let you know that I cannot really be satisfied with the
>> response.  I have pointed out loose ends in OWL 2 that go back to even
>> looser ends in OWL 1.  We should not bury our head in the sand and
>> argue: We cannot change sth because this would break backward
>> compatibility with OWL 1.
>> 
>> Now it is the time to get up the nerve to do sth that appears to be a
>> serious flaw :-)
>> 
>> Best regards,
>> 
>> Ralf
>> 
>> 
>> 
>> From: Michael Schneider
>> 
>> Dear Ralf,
>> 
>> Thank you for your comments
>> <http://lists.w3.org/Archives/Public/public-owl- comments/2009Jan/0059.html>
>> on the OWL 2 Web Ontology Language last call drafts.
>> 
>> Your mail actually contains three distinct comments. This response
>> exclusively covers your first comment. There will be additional
>> responses to your other two comments.
>> 
>> In your first comment, you state:
>>   I strongly recommend to change the OWL2 specification in such a way
>>   that data properties are always functional.
>> 
>> The working group acknowledges that by applying the approach
>> you mention in your comment it would indeed be sufficient
>> if all data properties would be functional.
>> 
>> However, the working group is aware of the fact that the
>> original OWL language did not restrict data properties to
>> be functional. Therefore, restricting data properties to be
>> functional in OWL 2 would break backwards compatibility with OWL.
>> 
>> For this reason, the working group has decided not to make
>> the requested change to OWL 2.
>> 
>> 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,
>> Michael Schneider
>> on behalf of the W3C OWL Working Group
>> 
>> 
>> 
>> http://lists.w3.org/Archives/Public/public-owl-comments/2009Jan/0059.html
>> From: Ralf Moeller [mailto:r.f.moeller@tu-harburg.de]
>> 
>> 1. I think it is a severe problem not to restrict data properties to
>> functional properties by definition.  Many problems with implicit
>> cardinality restrictions occur if the range of data properties is
>> restricted (e.g. via range specs such as xsd:int or xsd:integer with
>> arbitrary conjunctions of datarange specifications inclusing facets with
>> minInclusive and maxInclusive). Implicit cardinality restrictions
>> emerge, and this makes the implementation very difficult, and IMHO the
>> semantics is hard to understand.  Further, some facets such as
>> owl:length imply number restrictions for strings.  I have no idea, how
>> to deal with the owl:pattern facet (decidability problems?).
>> 
>> Arbitrary data properties are not needed: If, for instance, one might
>> want to use multi-value data properties for multiple names of a Person,
>> say, one can always introduce domain objects of class PersonName with a
>> single-value data property namestring.  PersonNames can be set into
>> relation to Person as usual via a role hasName, say. It is easy to
>> restriction the number of names, etc. With this kind of represenation we
>> can associate additional information with person names such as, for
>> instance, whether a name is a nickname or not.
>> 
>> If we say (at-least 2 hasName) then it is not guaranteed that the (two
>> or more) PersonName instances have different namestrings. If hasName was
>> a data property, this would be implied, leading to very tricky
>> constraints, which would make a sound and complete implementation very
>> difficult in the context of Aboxes and additional at-most restrictions
>> for the hasName data property.
>> 
>> I strongly recommend to change the OWL2 specification in such a way that
>> data properties are always functional.
>> 
>> 
>> 
>> 
> 
> -- 
> 
> Ivan Herman, W3C Semantic Web Activity Lead
> Home: http://www.w3.org/People/Ivan/
> mobile: +31-641044153
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Received on Friday, 13 March 2009 11:21:59 UTC