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Re: [ontolog-forum] orthogonal

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Ed Barkmeyer <edbark@xxxxxxxx>
Date: Tue, 04 Mar 2008 12:55:39 -0500
Message-id: <47CD8D1B.3000904@xxxxxxxx>
Schiffel, Jeffrey A wrote:    (01)

> An ontology is intended to define the terms of a domain, and the
> relationships among the terms. This allows for information exchange
> among agents, human or machine. It enables semantic interchange.    (02)

Well, having a shared ontology "enables semantic interchange" within the 
limits of what is actually shared.  In practice, many of the concepts 
required for an interchange do not have formal definitions, and the 
ontologies treat them as "primitive concepts" with natural language 
definitions and some formal properties that are helpful in identifying 
the intent (and useful in reasoning about them).    (03)

If you think Cairo is a city in Egypt, and I think Cairo is a city in 
Illinois, then we know we are talking about different places; but if the 
shared ontology only tells us that Cairo is a city, we may think we are 
talking about the same place.    (04)

> If two agents, each using an ontology, cannot exchange terms that can be
> fitted into the respective ontology each is using, then they must be
> using different, non-overlapping ontologies.  These two ontologies would
> be orthogonal. No term or relation in one ontology would have meaning in
> the other. The ontologies would be mutually exclusive.    (05)

This is a significant overstatement.  It is not at all necessary that 
the two ontologies be "mutually exclusive" in the sense that Jeffrey 
gives -- no concept in either theory can be grounded in the other.
Two agents can do business only if each understands ALL of the terms 
used by the other agent that are critical to the "business interchange". 
  If there exists ONE critical term that is not comprehensible to one of 
the agents, then those two agents cannot do that business.  If there are 
10 critical concepts and the overlap is 9 out of 10, that is not enough. 
  (We agree that I will make the missiles go up, but I don't understand 
where they are to come down. Do we have a deal?)    (06)

-Ed    (07)

Edward J. Barkmeyer                        Email: edbark@xxxxxxxx
National Institute of Standards & Technology
Manufacturing Systems Integration Division
100 Bureau Drive, Stop 8263                Tel: +1 301-975-3528
Gaithersburg, MD 20899-8263                FAX: +1 301-975-4694    (08)

"The opinions expressed above do not reflect consensus of NIST,
  and have not been reviewed by any Government authority."    (09)

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