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[protege-discussion] Not on Properties

Martin Kuba makub at ics.muni.cz
Wed Jan 4 07:06:10 PST 2012


Dne 4.1.2012 15:42, mar napsal(a):
> Thanks for the post.
>
> I have defined two classes A and B in an OWL file (attached). Both are
> subclasses of class 'Topic' and B is the complement of A. The reasoner can
> successfully infer the individuals of A but not B.
>
> My intention for B is to get all the individuals of 'Topic' which are NOT
> individuals of A.
>
> How can it be done?

You did it right, the B class as the complement of A contains
all individuals that are known not to be in A.

The problem you are experiencing is caused by OWA - Open World Assumption.

Your ontology contains assertions that w1,w2,w3 are connected by P with
o1,o2,o3 respectively. However it is not known from your ontology whether
o1,o2,o3 are connected by P to some Topic. In the open world of OWL,
they may be connected, or they may be unconnected, it is not known.

It is difficult to provide an assertion that would, for example,
ensure that o1 is *not* in A. For example, if Topic members would be
completely enumerated by making Topic equivalent to {o1,o2,o3,w1,w2,w3},
and providing *negative* property assertions for every P relation
that does not exist.

Best regards

Martin
-- 
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CERIT-SC                               Martin Kuba
Institute of Computer Science    email: makub at ics.muni.cz
Masaryk University             http://www.ics.muni.cz/~makub/
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