W3C home > Mailing lists > Public > www-rdf-logic@w3.org > November 2000

Re: Equality and subclass axioms

From: Jeff Heflin <heflin@cs.umd.edu>
Date: Mon, 27 Nov 2000 13:18:10 -0500
Message-ID: <3A22A562.447E2D4F@cs.umd.edu>
To: Ian Horrocks <horrocks@cs.man.ac.uk>
CC: Jim Hendler <jhendler@darpa.mil>, www-rdf-logic@w3.org
Ian Horrocks wrote:
> You didn't "negate" my axiom (you can never do that), you just added some
> additional information (an additional constraint). Assuming it is true
> that no model can allow triangles that are both three and four-sided, then
> this is an example of the kind of "over-constraining" that I mentioned in
> my email: our ontology now constrains allowable models to the extent that
> none can ever contain an instance of triangle (i.e., we can infer that
> triangle is equivalent to the class "Nothing"). If we use a reasoner to
> check the ontology generated by our crawler, then it will detect this
> fact, and can alert an intelligent (possibly human) agent to the fact that
> there may be a problem with the axioms relating to triangle.

But how can a system know when a particular definition is
"over-constrained" and when an equivalence to "Nothing" is actually
intended? Is a human going have to step in every time "Nothing" is
defined and say, "Yes, I really meant 'Nothing'?" I hope not, because I
can see ontology integration as a frequent occurence. I think that
semantic search engines will need to be able to integrate ontologies on
the fly to meet the needs/context of each query issued by a user. I
don't believe you can have a single integrated ontology that works for
all queries.

Received on Monday, 27 November 2000 13:18:25 UTC

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