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RE: Part II of my answers to PFPS' review of the RDF-Based Semantics

From: Michael Schneider <schneid@fzi.de>
Date: Mon, 15 Sep 2008 17:28:48 +0200
Message-ID: <0EF30CAA69519C4CB91D01481AEA06A0B98CE1@judith.fzi.de>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: <public-owl-wg@w3.org>
Hi Peter!

For the n-ary datatypes, I have extended the Editor's Note at the beginning
of the document by adding a reference to your mail:

 
<http://www.w3.org/2007/OWL/wiki/index.php?title=RDF-Based_Semantics&diff=12
938&oldid=12933>

For annotation, you are right of course. I added the "some":

 
<http://www.w3.org/2007/OWL/wiki/index.php?title=RDF-Based_Semantics&diff=12
939&oldid=12938>

I have eventually removed the Review Comment, which cited your original
review mail, since it is not needed anymore.

Thanks a lot,
Michael

>-----Original Message-----
>From: Peter F. Patel-Schneider [mailto:pfps@research.bell-labs.com]
>Sent: Monday, September 15, 2008 3:29 PM
>To: Michael Schneider
>Cc: public-owl-wg@w3.org
>Subject: Re: Part II of my answers to PFPS' review of the RDF-Based
>Semantics
>
>I'm just responding to any remaining open points.  I'm fine with the
>responses to my other points.
>
>From: "Michael Schneider" <schneid@fzi.de>
>Subject: Part II of my answers to PFPS' review of the RDF-Based
>Semantics [RE: Initial comments on OWL 2 Full Semantics]
>Date: Sun, 14 Sep 2008 20:15:14 +0200
>
>[...]
>
>> Peter F. Patel-Schneider wrote on September 03, 2008:
>
>[...]
>
>Nary datatypes:
>
>> >- Table 4.7 needs to be augmented with the conditions for nary
>some/all
>> >  as follows:
>> >  if l is the sequence p1,...,pn in IDP
>> >  - <x,c> in IEXT(IS(owl:someValuesFrom))
>> >    <x,l> in IEXT(IS(owl:onProperties))
>> >    then
>> >    ICEXT(x) = { y | exists z1, ..., zn  <y,zi> in IEXT(pi) for each
>> >  1<=i<=n
>> >                                         and <z1,...,zn> in ICEXT(c)
>}
>> >  - <x,c> in IEXT(IS(owl:allValuesFrom))
>> >    <x,l> in IEXT(IS(owl:onProperties))
>> >    then
>> >    ICEXT(x) = { y | forall z1, ..., zn  <y,zi> in IEXT(pi) for each
>> >  1<=i<=n
>> > imply <z1,...,zn> in ICEXT(c) }
>>
>> >- The above change removes the need for Table 4.9.
>>
>> The main problem with the above semantic conditions (or more
>generally:
>> with n-ary datatypes in OWL 2 Full) is that it requires to have n-
>tuples
>> as instances of the class c:
>>
>>   "<z1,...,zn> in ICEXT(c)"
>
>Well, you can consider this either a problem or a feature.  :-)
>
>> This isn't supported by RDFS, and at least not yet by OWL 2 Full. An
>> n-tuple is not an individual in the universe (just as a binary tuple
>in
>> the property extension of some property is not an individual), and
>> therefore cannot be a member of the class extension of some class.
>
>Hmm.  Not really.  RDF and RDFS "support" lots of things in the domain,
>including n-tuples, sets, philosophical attitudes, etc., all of which
>can perfectly easily belong to classes.  Of course, RDF and RDFS don't
>require any of these kinds of things to be in the domain, nor to be in
>any particular class.
>
>> What probably needs to be done is to come up with a new sort of
>> extension: A "nary-datarange extension" IDEXT_n(.), which allows to
>> state:
>>
>>   "<z1,...,zn> in IDEXT_n(c)"
>>
>> Fortunately, it is not a problem in RDF to assign different kinds of
>> extensions to the same individual, and these extensions do not even
>need
>> to have to be related with each other (e.g.: for some
>> class/property-individual w ICEXT(w) does not be related to IEXT(w)).
>
>I don't see that there is any reason in RDF or RDFS that the class
>extension of some datatypes and data ranges cannot be tuples.  Thus I
>don't see any need to introduce another semantic extension function.
>
>> However, there will still be a few problems:
>>
>>   * Until now, the range of someValuesFrom and allValuesFrom was IC.
>Now
>> the range would also need to cover all individuals, which have some
>> nary-datarange extension for arbitrary n.
>
>As above, I don't see any reason to not allow datatype classes whose
>class extensions have tuples in them.
>
>>   * The above semantic conditions should be more specific by entailing
>> that c is an n-ary datarange.
>
>Yes, probably.
>
>> Datatype complements are hit by this problem, too.
>
>I don't see a particular problem.
>
>> I have done the following: I added your proposed semantic conditions
>> to the Restrictions table, and removed the separate table.  Further, I
>> added comprehension principles to the "Comprehension Principles for
>> Restrictions" table.
>
>> I also added an editor's note to the beginning of
>> the document, which explains the problem. I will deal with this
>problem
>> after the WD submission, because I will need some time to think about
>> it.
>
>Having an editor's note for n-ary datatypes is fine by me.
>
>
>Annotations:
>
>> I have taken your proposed introductory text as is, with the
>> slight exception that I removed the "some" in "for some axiom
>> annotations" (I did not understand the "some", so please tell me what
>it
>> means, then I will put it in again).
>
>Only some annotations need this reification.  Annotations on entities
>and annotations on certain axioms (the few that have their own main
>blank node) do not need the reification process.
>
>> I also exchanged the semantic condition by the two you propose
>> above. But I am not really happy with having two semantic conditions,
>> and with having the typing triples for owl:Axiom and owl:Annotation in
>> their LHS. So I would like to discuss this with you, because I believe
>> that my original one is sufficient (we can defer this discussion a
>bit,
>> I added an EdNote.)
>
>This can be deferred.
>
>[...]
>
>> Regards,
>> Michael
>
>peter

Received on Monday, 15 September 2008 15:29:29 UTC

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