- From: Pat Hayes <phayes@ihmc.us>
- Date: Wed, 16 Sep 2009 15:10:56 -0500
- To: Chimezie Ogbuji <chimezie@gmail.com>
- Cc: Alan Rector <rector@cs.man.ac.uk>, Uli Sattler <sattler@cs.man.ac.uk>, Milan Zdravkovic <milan.zdravkovic@gmail.com>, public-owl-dev@w3.org
On Sep 16, 2009, at 9:50 AM, Chimezie Ogbuji wrote: > On Tue, Sep 15, 2009 at 4:24 AM, Alan Rector <rector@cs.man.ac.uk> > wrote: >> Well, no, you cannot (validly) conclude this. This is a non-monotonic >> inference, which is not supported by the OWL semantics. While it >> may work in >> particular cases where you know that your data is complete in the >> required >> sense, it is not good practice to use such inference patterns in >> OWL, as >> they will (not may, but WILL) break in some cases. Think building a >> glass >> building over a known seismic fault. >> >> Pat Hayes > >> The difficulty with such reasoning patterns is that they only work >> when you >> can >> complete the knowledge base so that it is fully constrained. >> In most of our biomedical models, we can rarely be certain enough >> that all possibilities have been covered to reason that the only >> possibilities left over are true, only that they might be and may >> ]be worth further investigation. > > True, but I've found (in practice) that non-monotonic reasoning > matches well with the intuition behind clinical medicine and the way > electronic patient data can be recorded as RDF (mostly using strict > data entry controls where it is important to assume at least a portion > of the data is complete in order to make reasonable inferences from > it) Well, let me rephrase my point somewhat differently. If you use this inference pattern, and come to rely on it, and then in some case you find it delivers false conclusions, do not complain to anyone about RDF or OWL, or complain to the proprietors of the RDF or OWL reasoner you are using. Do not say that your reasoner is broken. Go instead to whoever gave you the data you were using and upon whose completeness you were relying, to serve the writs, or voice the complaints, or whatever. Pat > >> Although we have sometimes used this kind of reasoning on very >> restricted >> data entry problems with multiple constraints where we can be sure >> that they >> can all be covered. In those cases the non-monotonicity is an >> advantage, >> although I would try to confine it to increasingly large queries >> rather than >> the KB itself. As we learn more, we add it to the query, so that >> query gets >> larger and the number of >> possible answers to the remaining questions gets fewer. >> This sort of reasoning used to be supported in the Protege Query >> tab, but is >> no longer. >> Regards >> Alan > > -- Chimezie > ------------------------------------------------------------ IHMC (850)434 8903 or (650)494 3973 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32502 (850)291 0667 mobile phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Received on Wednesday, 16 September 2009 20:12:53 UTC