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Re: what is the "semantic core" of DAML-S?

From: Drew McDermott <drew.mcdermott@yale.edu>
Date: Sat, 20 Sep 2003 17:28:09 -0400 (EDT)
Message-Id: <200309202128.h8KLS9H19493@pantheon-po03.its.yale.edu>
To: www-ws@w3.org


   [Joachim Peer]
   > a) surely everything can be represented somehow by DL ontologies, and
   > DAML-S does just that.

   [Bijan Parsia]
   Uh. That seems false to me, unless you mean, "some representation can 
   be encoded in" a la how DRS encodes more complex logical formulae in 
   plain RDF. Not the most useful sense of "able to represent", IMHO.

It seems false to me, too.  I think what has happened is that people
have gotten used to expressing some "ontological" facts in DLs, and
think of stuff that can't be so expressed as requiring something else,
like "rules."  The conclusion that everything "ontological" can be
expressed in DLs then becomes a tautology.

Relatively trivial axioms can be hard to express in DLs, such as

   If b is between a and d, and c is between b and d, then c is
   between a and d.

I see no reason why this should be excluded from an ontology.

(Someone correct me if there's some obvious way to do this using roles
equalities or whatever.  The hard part is not representing the trinary
relationship; we can do that with the standard tricks.)

-- 
                                             -- Drew McDermott
                                                Yale Computer Science Department
Received on Saturday, 20 September 2003 17:28:12 GMT

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