Hi Adam, All --
You wrote...
The intent of the engineer who created the term may be different
from that of a later engineer who wants to add semantics to the term.
I don't see any general solution to this other than controlling the
upper ontology to a degree by having a single architect, and well
trained collaborators.
A proposed general solution is surely the use of URIs in the semantic
web.
Cheers, -- Adrian
Adam Pease wrote:
Hi Duane,
A good way to check this issue I think is to look at SUMO. The only
"primitives" that are undefined in the ontology are the logical
operators, which are defined in the SUO-KIF language specification.
Every term builds up definitions from the logical operators, and then
other terms. I don't believe there are any circular definitions in the
ontology, although I'd be glad to discuss any that appear so, since
that would be a bug.
Ron Schuldt brings up the issue of language, which is often a problem
with informal ontologies that do not separate logical terms from
linguistic tokens. A formal ontology such as SUMO must distinguish
language from logic to avoid the sort of confusion or imposition he
describes. SUMO does this by keeping WordNet synsets and SUMO terms
related but separate.
Lisa brings up an interesting issue about "semantic shift". In a
formal ontology, terms mean exactly what the axioms say they mean.
However, very few terms in the common sense world have necessary and
sufficient definitions. Each new axiom in which a term appears adds to
its formal definition. It is quite possible to use a term in a way
that is consistent with its semantics so far, and then extends those
semantics. If there are a lot of terms in an ontology, the engineer
may make an error in the use of the term. Testing for logical
contradictions or against a regression test suite can help. Because
common sense terms don't often have sufficient (in the mathematical
sense) definitions they are unfinished products. The intent of the
engineer who created the term may be different from that of a later
engineer who wants to add semantics to the term. I don't see any
general solution to this other than controlling the upper ontology to a
degree by having a single architect, and well trained collaborators.
Fortunately, that's the case for SUMO.
Adam
At 07:25 AM 5/3/2005, Duane Nickull wrote:
Chris Menzel wrote:
O
Well, if a definition of a concept *does* make use of concepts that are
axiomatized in terms of concept being defined, then it is just a bad
definition.
Chris:
This is what I wanted to explore. Look at the english dictionary - it
uses all the words that are defined in the dictionary to define the
words in the dictionary. A great deal of care is taken to avoid direct
inclusion of terms in circular references however most of the words
defined by the dictionary are probably used in definitions of other
words.
Is that really an ontology? Are there formulas that state the number
of levels a word must be reasonably not used in a set of definitions
until it is used again?
Example:
1. A Company is a military unit, typically consisting of 100-200
soldiers
2. A Battalion is an army unit usually consisting of a headquarters and
three or more companies
3. A Division is an military unit large enough to sustain combat
4. A Regiment is a military unit, larger than a company and smaller
than a division
In the definition of Regiment #4, we have used words to explain it that
were just defined themselves #1,3. #2 is superfluous yet aids in
providing semantics to some degree (or does it?).
Sorry to once again be the loose cannon ;-)
Duane
***********
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http://www.adobe.com
Vice Chair - UN/CEFACT Bureau Plenary - http://www.unece.org/cefact/
Adobe Enterprise Developer Resources -
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