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Re: raised in comment: owl:class still needed? Does this effect Test LC?

From: Jos De_Roo <jos.deroo@agfa.com>
Date: Sat, 24 May 2003 23:09:49 +0200
To: "Jim Hendler <hendler" <hendler@cs.umd.edu>
Cc: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, www-webont-wg@w3.org
Message-ID: <OFCC867E76.5BEC37E6-ONC1256D30.00741808-C1256D30.00744285@agfa.be>


Last Thursday Jim Hendler wrote:
>At 8:23 AM -0400 5/22/03, Peter F. Patel-Schneider wrote:
>>From: Jim Hendler <hendler@cs.umd.edu>
>>Subject: raised in comment: owl:class still needed? Does this effect Test
LC?
>>Date: Wed, 14 May 2003 11:19:38 -0400
>>
>>>
>>>  One part of one of our public comments from RDF Core asks:
>>>
>>>  RDFCore: Comments on OWL Reference
>>>
http://lists.w3.org/Archives/Public/public-webont-comments/2003May/0004.html
>>>
>>>     #owlref-rdfcore-owl-class-denotation
>>>     It has been suggested to
>>>     RDFCore that owl:Class is not needed.  RDFCore requests the
>>>     creation of test cases to clearly illustrate the differences
>>>     between owl:Class and rdfs:Class.
>>>
>>>  I'd like to see such a test (or tests) in our LC Test document, as it
>>>  is likely that we will get this same or similar comment again.  If
>>>  such a test cannot be generated, then I believe we need to reopen
>>>  issue 5.20 as it was determined at the Bristol f2f:
>>>
>>>    re 5.20 Should OWL provide synonyms for RDF and RDFS objects? no,
>>>  owl should not have synonyms; owl:Class is not a synonym.
>>>
>>>  (this is part of a long thread and the resolution included this and
>>>  other statements, but I believe the above is where the WG officially
>>>  agreed owl:class was not a synonym)
>>>
>>>  and appropriately change our documents.
>>>
>>>  Peter/Ian (or anyone else) - can one of you remind the WG the
>>>  difference and design a test case for it?
>>
>>[copied out of another message]
>>
>>The RDFS-compatible semantics for OWL DL heavily depends on owl:Class
(more
>>precisely, on IOC, the class extension of owl:Class).  If the distinction
>>between owl:Class and rdfs:Class was removed the semantics would be quite
>>different.
>>
>>Test cases are rather hard to come by, as OWL DL is designed so as to
>>prevent one from interacting with classes that are not OWL classes.
>>
>>However, if one looks at RDF graphs that are not in OWL DL one can see
the
>>difference.  For example,
>>
>>ex:a rdf:type rdfs:Class .
>>ex:ia rdf:type ex:a .
>>
>>currently does not OWL DL entail
>>
>>ex:ia rdf:type _:i .
>>_:i owl:intersectionOf _:l1 .
>>_:l1 rdf:type rdf:List .
>>_:l1 rdf:first ex:a .
>>_:l1 rdf:rest rdf:nil .
>>
>>but it would if owl:Class was replaced with rdfs:Class in the semantics.
>>
>>peter
>
>Looks good.

I was thinking that too, but the comment was

>>>     RDFCore that owl:Class is not needed.  RDFCore requests the
>>>     creation of test cases to clearly illustrate the differences
>>>     between owl:Class and rdfs:Class.

and although that test case illustrates the differences
it is not showing that owl:Class is needed.

>             What about another one that somehow reflects that
>rdfs:class is a member of rdfs:class, but owl:class is not a member
>of owl:class?

Maybe owl:Class rdf:type owl:Class is not a legal DL document
just as rdfs:Class rdf:type rdfs:Class isn't, but that doesn't
mean that it's not legal OWL (and a true statement); again it
is not showing that owl:Class is needed.

--
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/
Received on Saturday, 24 May 2003 17:10:22 GMT

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