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Re: Revisiting AllDisjoint (was Proposed (parital) response to Ken Laskey and questions for WG)

From: Jonathan Borden <jonathan@openhealth.org>
Date: Mon, 14 Jul 2003 18:05:12 -0400
Message-ID: <013701c34a54$02c30770$b6f5d3ce@svhs.local>
To: "webont" <www-webont-wg@w3.org>, "Jim Hendler" <hendler@cs.umd.edu>
Revisiting AllDisjoint (was Proposed (parital) responsDifferent kinds of cancer, for example, are hardly disjoint: one person might have any number of different cancers -- really. If we are going to revisit anything that might actually improve something like GALEN, how about qualified cardinalities?

Jonathan

----- Original Message ----- 
  From: Jim Hendler 
  To: webont 
  Sent: Monday, July 14, 2003 5:32 PM
  Subject: Revisiting AllDisjoint (was Proposed (parital) response to Ken Laskey and questions for WG)


  I would like to take a moment to see what people think about having to reopen this issue (or possibly move forward over an objection):


  In a conversation (non electronic) with Ken Laskey, who has again raised the issue of having an owl:allDisjoint construct (mirroring the allDifferent construct), I pointed him to Dan Connolly's [1] earlier response to this issue.  Ken indicated that he was not likely to accept this answer, and in conversation he brought up many use cases where this would be needed.  Basically, he disputes our contention that since this occurs in "class space" it is likely to be just a small number -- as he points out,  we already have a number of ontologies in OWL that are quite large (the NCI ontology and the GALEN ontology, are two examples).  In these ontologies, there are numerous cases where one would want to take a large set of classes (for example the different kinds of cancers) and make it explicit that some of these are disjoint (and thus others aren't necessarily) -- even though N is comparatively small, say 100 (remember the total number of classes in NCI is about 17000), this takes ~(N^2)/2 = 5,000 (!!) OWL statements. 
    Further, Ken points out that even in some of the smaller ontologies we've created, the number of classes and the number of disjoint classes can be almost identical (for example, military ranks are mutually disjoint within services, but not always between - someone cannot be an Army Lieutenant and and Army Captain, but there are rare cases where someone is "dual hatted" as an Army Colonel and a Navy Captain, for example).  Here's the odd thing -- the number of classes in the military ranks ontology would be about 50 (if one includes officers and non-officiers), which would require on the order of 1000 disjoint statements --significantly dwarfing the size of the original ontology!
   Note that in none of these use cases are we talking disjoint unions per se (although I suppose one could create a workaround if one had a disjointunion construct).
   I think the N^2 problem in the size of the ontologies we're already seeing might be evidence to reopen this issue.  Alternatively, if there is a decent workaround, we might want to document that workaround and not add this construct.  We can also try to move forward over Ken's objection, although my preference would be to look for a way not to.

   -JH
  p.s. Please note that this would NOT require any new semantics or any major new syntax - semantically we already have the ability to assert the pairwise disjuncts, and semantically this could be done using the same construct we created for allDifferent.




  [1] http://lists.w3.org/Archives/Public/public-webont-comments/2003Jun/0038.html


-- 

  Professor James Hendler                           hendler@cs.umd.edu
  Director, Semantic Web and Agent Technologies         301-405-2696
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Received on Monday, 14 July 2003 18:05:19 GMT

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