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Re: ISSUE-55 (owl:class) (and ISSUE-56 repairsomerdf)

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Sun, 2 Dec 2007 16:52:20 -0500
Message-Id: <1EDA8614-D3AB-46AD-8CD6-5CB9A7855BA1@gmail.com>
Cc: Jim Hendler <hendler@cs.rpi.edu>, OWL Working Group WG <public-owl-wg@w3.org>, "Deborah L. McGuinness" <dlm@ksl.stanford.edu>
To: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>

I'm not sure I consider this a best practice or UDF issue. It is  
related to ISSUE-56, which I have been thinking of as possibly  
related to fragments.

Here is another way to think about it.

Suppose that we added an axiom (in OWL-Full, for the moment) in the  
spirit of
(1) rdfs:Class rdfs:subClassOf owl:Class

Let's also assume that if one substituted owl:Class for rdfs:Class  
everywhere in the ontology, the ontology would be considered OWL-DL.

With the addition of (1), then, would we not have a "fragment" of OWL  
Full that had could be considered to have the same expressivity as  


On Dec 2, 2007, at 2:56 PM, Deborah L. McGuinness wrote:

> Ian Horrocks wrote:
>> See the emails on this issue, in particular http://lists.w3.org/ 
>> Archives/Public/public-owl-wg/2007Nov/0263.html and http:// 
>> lists.w3.org/Archives/Public/public-owl-wg/2007Nov/0258.html, for  
>> an explanation of the significant and not fully understood  
>> technical difficulties.
>> IMHO, if it goes anywhere this should go in some UFD giving advice  
>> on "repairing" ontologies (see also ISSUE-56).
> this is an interesting point.
> there may be some number of clarification issues such as this.   
> they may be perceived as some best practices kinds of issues.
> if we look at the existing model for the documents for owl 1.0,  
> this type of advice was not really included (although some flavor  
> of this was in the guide).
> this kind of information was more in the best practice working  
> group documents.
> i think there is room for a range of documentation that would be  
> useful.  Are you considering suggesting some documents that are in  
> the best practice flavor?  and would those come out of this working  
> group (or out of a swbp follow on group)?
> i am also wondering if we want to consider a wiki-style faq option.  
> the reason i suggest that is if we wait for a follow on swbp group  
> to form and documents to come out, it will be a while.
> thanks,
> deborah
>> Ian
>> On 2 Dec 2007, at 18:27, Jim Hendler wrote:
>>> My request in raising the issue was that if we postponed it, we  
>>> needed a clear statement as to why the problem exists (and  
>>> several people have suggested adding the note that many reasoners  
>>> change rdfs:class to owl:class despite the semantic issue) --  
>>> saying " introduces significant and not fully understood  
>>> technical difficulties" does not satisfy what I asked this issue  
>>> to be addressed for.  Again, in studies of ontologies out there,  
>>> a great many OWL Full ontologies become OWL DL with this change,  
>>> I would think that it would therefore be incumbent on this group  
>>> to either encourage those users to use owl:class (by explaining  
>>> why they should) or make it clear they can still work with OWL DL  
>>> tools if they don't, but there are certain techniical risks  
>>> (which I must admit I still don't understand)  So if we postpone  
>>> this issue, which I'm okay with, it requires an explanation - and  
>>> that is where I think we (the OWL community) has failed to  
>>> date.   In fact, I've been suggesting to my students that they  
>>> use rdfs:class in many applications since OWL DL tools fix it,  
>>> and RDF-only tools don't reject it...  this is clearly wrong  
>>> semantically (Which I explain to the best of my limited ability)  
>>> but right from a practical point of view...
>>>   -JH
>>> On Dec 1, 2007, at 3:07 PM, Ian Horrocks wrote:
>>>> I'm tending to postpone this issue on the grounds that it  
>>>> introduces significant and not fully understood technical  
>>>> difficulties.
>>> "If we knew what we were doing, it wouldn't be called research,  
>>> would it?." - Albert Einstein
>>> Prof James Hendler http://www.cs.rpi.edu/~hendler <http:// 
>>> www.cs.rpi.edu/%7Ehendler>
>>> Tetherless World Constellation Chair
>>> Computer Science Dept
>>> Rensselaer Polytechnic Institute, Troy NY 12180
Received on Sunday, 2 December 2007 21:52:39 UTC

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