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: Tue, 28 Nov 2000 11:19:00 -0500
Message-ID: <3A23DAF4.AF4C49AF@cs.umd.edu>
To: Ian Horrocks <horrocks@cs.man.ac.uk>
CC: Jim Hendler <jhendler@darpa.mil>, www-rdf-logic@w3.org
Ian,

I don't purport to have all the answers either, I just want to make sure
that important questions like these are raised.

However, I would like to disagree with your statement that if you
restrict the language so that no conflicts can occur then the language
would be useless. A datalog-like language  (w/out negation) would not
have logical inconsistency problems. SHOE, is one such language, and
although I'll admit you cannot express many things that might be desired
in it, it is far from useless.

Jeff

Ian Horrocks wrote:
> 
> On Mon, 27 Nov 2000, Jeff Heflin wrote:
> 
> >
> > 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.
> 
> I agree that there are many difficult questions here which I don't claim
> to know the answer to. What I was trying to say was that, in my humble
> opinion:
> 
> 1. Trying to restrict the language so that no "conflicts" can ever arise
> is not a viable solution: you would have to get rid of a lot more than
> just equivalence axioms, and the resulting language would be so
> impoverished as to be useless (c.f. the failure of early DL systems that
> tried to make reasoning "easy" by severely limiting the expressive power
> of the language).
> 
> 2. Using reasoning to identify such conflicts can only help. What you do
> about conflicts once they have been identified is your problem. You are of
> course at liberty to ignore them, in which case you are no worse off than
> you would have been without reasoning (unless you take the view that "what
> I don't know can't hurt me").
> 
> Ian
Received on Tuesday, 28 November 2000 11:19:07 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 2 March 2016 11:10:33 UTC