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Re: [ontolog-forum] Ontology vs OWL implementation

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Ed Barkmeyer <edbark@xxxxxxxx>
Date: Fri, 02 May 2008 18:23:04 -0400
Message-id: <481B9448.8000306@xxxxxxxx>
Chris Menzel wrote:    (01)

>> My personal preference is a much stronger definition:
> I'm not sure it's stronger.    (02)

Agreed.  From a logician's point of view, my definition is so weasel 
worded that it can hardly be said to be well-defined, let alone stronger.    (03)

The original purpose of a "semantic web ontology", as distinct from 
"logical theories", was to provide a set of terms and relationships that 
would be used to markup documents to facilitate search, by allowing the 
recognition of a subject in context.    (04)

What I mean to eliminate is the taxonomies and thesauri that simply 
introduce terms, without any effort to "define" them.  They still 
facilitate search, but it is not possible for a reasoner to do much with 
them.    (05)

>> A formal language that provides a means of definition of a term  
>> using a syntax with a well-defined semantics that supports  
>> (automated) reasoning is an "ontology language".
> Ok, let's say KIF, which is supported by the Schulz/Halcomb Tau  
> reasoner.    (06)

Sure.    (07)

>> A model...
> I assume you really mean a set of sentences, and not a model in the  
> model theoretic sense.    (08)

Yes.  That is exactly what I mean.  The issue that Cati raised was 
"ontologies" vs. "information models", so I took it that, in that 
terminology context, they are both subtypes of "model" = a set of 
sentences that describe some abstraction of someone's world.    (09)

>> ...captured in that language is an "ontology" if and only if most of  
>> the terms it introduces are defined in the model using the  
>> definition mechanisms of the formal language (possibly including  
>> references to terms that are formally defined elsewhere).
> Ok, let's suppose our specific KIF language has the predicates P and  
> Q.  I define them thus:
> (forall (x y) (iff (P x y) (= x y)))
> (forall (x y) (iff (Q x y) (not (P x y))))
> By your definition, this is an ontology.  (Call it the "Identity and  
> Difference (I&D)" ontology. :-)  Maybe that's ok with you -- it's  
> certainly ok with me.  But I got the impression you had something more  
> discriminating in mind.    (010)

I am happy to call this an "ontology".  That it is a "trivial" or 
"degenerate" case is not a problem.  It is axiomatic and it is closed.
It is vastly preferable to calling a big collection of undefined terms 
with a few subsumption relationships and no other identifiable axioms an 
"ontology".    (011)

-Ed    (012)

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    (013)

"The opinions expressed above do not reflect consensus of NIST,
  and have not been reviewed by any Government authority."    (014)

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