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[OEP] "Classes as values": summary of the discussion so far and second draft

From: Natasha Noy <noy@SMI.Stanford.EDU>
Date: Tue, 27 Apr 2004 12:56:41 -0700
Message-Id: <005DA650-9885-11D8-84C6-000A958B5C28@smi.stanford.edu>
To: swbp <public-swbp-wg@w3.org>

As promised, you can find the second draft of the "classes as values"  
note at
http://lists.w3.org/Archives/Public/www-archive/2004Apr/att-0091/ 
ClassesAsValues-v2.html

Thanks a million to everyone for all the thoughtful feedback (and for  
kind words along the way). I think the discussion is not over yet, I  
tried to address some of the points that seemed less controversial and  
left some of the discussions (cf my replied to Alan [1] and Aldo [2] up  
in the air for the moment).

In lieu of summary of the discussion, here is a list of main changes in  
this version.

Running example: it was clear that my example of annotating images of  
lions was a very bad one, since it wasn't clear whether a subject of an  
image (in the normal English interpretation of the term) is the  
specific lion in the picture or lions in general. I was trying to  
address the latter with the pattern and that's what I am trying to  
stick to (other cases are for other patterns, I think). So, the example  
now is subjects of books, rather than images, which is a bit less  
ambiguous. A book about lions has the class or subject Lion as its  
subject, and a specific living breathing creature.

Approach 2b is eliminated. It used rdfs:isDefinedBy  to link instances  
of Subject with the corresponding classes (such as LionSubject and  
Lion), but the solution was no different (but more verbose) than  
Approach 4, which used annotation property. The only reason 2b was in  
OWL DL was because rdfs:isDefinedBy was an annotation property, since  
it still had a class as its value

Full solution in OWL and its different flavors. Deb pointed out in her  
template for patterns that each pattern should include a full text of  
the solution in OWL, which makes a lot of sense. I've added that at the  
end of each approach. Since I was mocking up all examples in Protege  
anyway, it was essentially no effort to add it in RDF/XML syntax, N3,  
and abstract syntax. So, take your pick :)

Outstanding discussion and other issues: Alan and Aldo suggested  
another approach which uses prototypes as values ([3], [4]). I think  
with this more narrow scope of the example (subjects of books rather  
than pictures), their solutions seem to address a somewhat different  
problem. But I am not sure if we have reached closure on that.

Also has also brought up the issue of ontological patterns vs pragmatic  
patterns [4]. I am not sure yet though is this is a use case to  
distinguish them explicitly here.

 From the public and private comments that I have received, it is clear  
that for each of the approaches, at least some people in the group  
consider them useful and would use them if they had to stay in OWL DL  
(and, for most, others consider them really bad and will not use them  
ever). So, I kept all of them for now.

Am I forgetting some other outstanding issues?

The rest are smaller changes that those looking for a higher-level  
summary can easily ignore:
- In approach 2, I made much more prominen the point that making  
subjects individual instances of the corresponding classes will make it  
inconsistent with having real animals instances of the same classes.  
Also changed the summary for that approach
- In approach 3, the rdf:type of subject individuals is now a single  
class Subject (distinguishing this case from 2, and allowing actual  
physical lions to be instances of the classes in the hierarchy)
- In approach 1, saying that something is in OWL Full is not saying  
much (after all,, all OWL DL ontologies are also in OWL Full). Rather  
than saying that "This ontology is in OWL Full", it now says "This  
ontology is in OWL Full, but not OWL DL".
- In approach 4, added a diagram illustrating the approach.
- Added a footnote anywhere allValuesFrom is used that in some cases  
someValuesFrom would be more appropriate.

Thanks a lot to everyone who has contributed to the discussion! And, as  
I pointed out earlier, I don't think we've reached closure on some of  
the issues, so, probably, there will be one more iteration.

Natasha

[1] http://lists.w3.org/Archives/Public/public-swbp-wg/2004Apr/0137.html
[2] http://lists.w3.org/Archives/Public/public-swbp-wg/2004Apr/0153.html
[3] http://lists.w3.org/Archives/Public/public-swbp-wg/2004Apr/0132.html
[4] http://lists.w3.org/Archives/Public/public-swbp-wg/2004Apr/0149.html
Received on Tuesday, 27 April 2004 15:56:48 UTC

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