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Re: LANG: owl:ontology

From: Christopher Welty <welty@us.ibm.com>
Date: Wed, 18 Sep 2002 09:49:23 -0400
To: www-webont-wg@w3.org
Message-ID: <OFD398F3AE.21E7E334-ON85256C38.004A7C12@pok.ibm.com>


In your example below, that the builder of URI2 may not have "intended" 
for all of URI1 to be loaded when importing URI1:foo is too bad.  One of 
the most common and (I think) important reasons to build a million-node 
graph around a set of symbols to to ensure those symbols are used 
correctly, and to prevent them from being used incorrectly.  The ontology 
helps to enforce that the intended meaning is maintained. 

If someone wants to import just one symbol from my ontology, then they 
have to get all of my ontology so that they get all the constraints and 
inter-relationships that help clarify the meaning of that symbol wrt 
others.   I *don't care* if that's what the user intended - that's what I, 
the designer of the ontology, intended: dont misuse my symbols!

If this isn't enforced, then borrowing symbols from other ontologies is 
meaningless and serves no purpose.  There is nothing to gain from using 
URI1:foo if you aren't getting all of the ontology around URI1:foo - you 
may as well just make up your own symbol in URI2, because that's all it 
is.  If you are borrowing URI1:foo because "you mean the same thing", then 
importing the whole ontology that enforces that meaning should have no bad 

Of course ontologies can always be built in a modular way so that if there 
is a small subset of the symbols that can be exported idependently of 
others (a top level ontology would be one kind of example) then they are 
all in a smaller ontology that is imported, but that is more of an 
engineering issue.


Jim Hendler <hendler@cs.umd.edu>
Sent by: www-webont-wg-request@w3.org
09/17/2002 09:57 PM

        To:     pat hayes <phayes@ai.uwf.edu>
        cc:     www-webont-wg@w3.org
        Subject:        Re: LANG: owl:ontology


what I have a problem with is the following

At URI1:
<owl:class rdf:ID="foo" />

(1,000,000 other assertions that appear in the graph)

At URI2:

<:bar owl:subclass URI1:foo />

(put in any owl:ontology and rdf:RDF syntax you want - but no 
owl:imports in URI2:)

In this case I have a real problem with merging the graphs -- the 
user is very unlikely to actually intend that those million facts 
which he or she may not even have read should be included.

This is the case I really care about.  For imports anything that can 
identify and merge graphs makes me happy - for this case, I care that 
we somehow scope what is included.  I would like this to have the 
same semantics as having one URI which contained

<owl:class rdf:ID="foo" />
<:bar owl:subclass :foo />

(i.e. nothing else from URI1: is to be included unless it is 
explicitly  mentioned.)

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 
Univ of Maryland, College Park, MD 20742                   240-731-3822 
Received on Wednesday, 18 September 2002 09:49:59 UTC

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