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[OEP] Closed vs Open World $swbpd

From: Uschold, Michael F <michael.f.uschold@boeing.com>
Date: Fri, 17 Dec 2004 15:58:04 -0800
Message-ID: <823043AB1B52784D97754D186877B6CF05C7893B@xch-nw-12.nw.nos.boeing.com>
To: <public-swbp-wg@w3.org>

We just encountered the time-honored 'problem' of what happens when a
user assumes/expects closed-world inference, and gets open world.

Unless two classes A and B are provably disjoint (possibly via an
explicit disjoint axiom), a DL reasoner will not conclude that A is in
the complement of B.

This can be seen as a feature, because it allows you distinguish between
"can't prove it" and "can prove that it is false".

It could also be experienced as a problem (read: big pain in the neck)
by a user who does not need to make that distinction, because it forces
them to add bunches of disjoint axioms.

This is a likely source of confusion for some users. 
It would be good if we could say something about this. Questions that
users may wish to be discussed/answered include:

*	are there any identifiable characteristics of a domain, which
suggest when you want an open vs. closed world reasoner?
*	does the Semantic Web infrastructure offer any closed world
reasoners?  
*	If not, then what do we say to a user who does not care to
distinguish not provable from provably not and finds it a nuisance to
add all those disjoint axioms? They are unlikely view as helpful, a
comment such as: "You should be glad to be forced to model your domain
more carefully".

I think that we should try and say something about this somewhere, it is
bound to come up over and over.
Is there a note that this topic might be covered in?
Should we have separate, short not on it?
Does anyone have enough expertise/experience to say something sensible
on the topic?

Alan Rector may know more about this than anyone, with all the users
encoding bio ontologies in DLs.

Mike


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Received on Friday, 17 December 2004 23:58:44 UTC

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