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Re: LANG: syntactic version for imports (and other things)

From: Jim Hendler <hendler@cs.umd.edu>
Date: Mon, 16 Sep 2002 22:55:00 -0400
Message-Id: <p05111703b9ac441f565b@[]>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, heflin@cse.lehigh.edu
Cc: www-webont-wg@w3.org

I now fully understand the difference in understanding between me and 
Peter - turns out there is something in the DAML+OIL model theory 
that I never realized -- according to separate info that I received 
from Peter and others, the following turns out to be legal DAML 

URI1 has an ontology called AAA, including class XXX

URI2 has an ontology called BBB,
and a class YYY that states it is a subclass of URI1:XXX.

if I understand correctly, however, I am told that this means that 
while YYY makes this claim, since it has no imports statement to AAA, 
it as if this subclass statement didn't exist.

I never realized this before, and think that if it is true, we should 
fix it --currently a large number of the DAML documents out there 
therefore do not mean what their authors intend -- we could tell them 
all they are wrong because they don't follow the model theory, but 
seems to me it might be better for us to make it possible for people 
to have some meaning when they link to items in other documents 
(instead of to whole ontologies) since they can do it anyway, and the 
average user will assume the "natural semantics" as opposed to the 
current situation (I put owl statements in my document but owl 
reasoners simply ignore them - yecch).

>  > One of
>>  the problems we got into with DAML+OIL is we didn't say what imports
>>  meant, and thus everybody interpreted it to mean whatever they felt
>>  like.
>Well, I think that the problem was that we thought that it was obvious what
>a DAML+OIL ontology was, and thus what imports meant.

no, I think several of us had different opinions, and we decided to 
move to the Working Group process to work out a solution.   I think 
we agreed what imports mean, but not what it meant to point to 
something without importing!


Professor James Hendler				  hendler@cs.umd.edu
Director, Semantic Web and Agent Technologies	  301-405-2696
Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742	  240-731-3822 (Cell)
Received on Monday, 16 September 2002 22:55:12 UTC

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