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Re: [ontology-summit] Defining "ontology"

To: "Ontology Summit 2007 Forum" <ontology-summit@xxxxxxxxxxxxxxxx>
From: "Uschold, Michael F" <michael.f.uschold@xxxxxxxxxx>
Date: Thu, 25 Jan 2007 08:21:05 -0800
Message-id: <4301AFA5A72736428DA388B73676A38105386642@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
The group will have to decide whether it wants its definition to be 
1) normative, and there hope expect that everyone else will follow and use this 
definition.  -or-
2) descriptive, which is to say merely reflects the ways that the term I used 
today.
3) a third way?    (01)

I have always believed that 1) is unachievable, people will always disagree. 
The more crisp the definition it, the more disagreement there is.
2) results in many different definitions whose common core amounts to:
  * has a set of terms reflecting concepts of interest in some domain -and-
  * has some degree of specification of the meaning of the terms    (02)

Every single thing I ever heard called an ontology has these two things (though 
sometimes the specification of meaning is thin or just implicit). What is 
different about the things people call ontologies are the various dimensions 
that have been mentioned here.  Degree of formality, amount of meaning 
specified, how meaning is specified, what the ontology is used for etc.    (03)

http://protege.stanford.edu/conference/2006/submissions/slides/1.2_Uschold.pdf    (04)

I believe a more constructive approach will be to 
1) accurately reflect the reality of the different ways that the term 
'ontology' is used. and then
2) choose a meaning that this group likes, and call it our own.     (05)

See part 1 of my Protégé keynote for a summary of these ideas reflecting my 
latest thoughts on the matter.
==========================
Michael Uschold
M&CT, Phantom Works 
425 373-2845
michael.f.uschold@xxxxxxxxxx  
==========================    (06)

----------------------------------------------------
COOL TIP: to skip the phone menu tree and get a human on the phone, go to: 
http://gethuman.com/tips.html     (07)



-----Original Message-----
From: John F. Sowa [mailto:sowa@xxxxxxxxxxx] 
Sent: Thursday, January 25, 2007 5:44 AM
To: Ontology Summit 2007 Forum
Subject: Re: [ontology-summit] Defining "ontology"    (08)

Leo, AJ, and Deborah,    (09)

Many of the proposed definitions of ontology are much too broad.
When all the useful and important, but peripheral things are thrown in, the 
difference between ontology and KR becomes blurred:    (010)

AJC> I read Deborah's paper, Leo's presentation and other
 > materials on ontology spectrum that were mentioned on this list.
 > I found it's a nice way to view how knowledge representation  > has been 
 >evolved. If I understand correctly, the ontology spectrum  > view implies the 
 >term "ontology" is used almost as the replacement  > for "knowledge 
 >representation".    (011)

It is important to distinguish two points    (012)

  1. What is required logically.    (013)

  2. What is important for other very important, but ancillary
     purposes:  efficient computation, development tools, etc.    (014)

The question of expressiveness is important for computational purposes, but its 
only logical effect is to determine how much of the subject domain can be 
stated or must be omitted.  Although that may be important for many purposes, 
it has no effect on the definition of what is or is not an ontology.    (015)

 From a strictly logical point of view, every ontology is a theory.
And a theory consists of two things:    (016)

  1. A base logic, whose syntactic details are irrelevant.  At
     the logic level, RDF, OWL, SQL, and any of the formalized
     versions of UML are all subsets of Common Logic.  The very
     important practical differences between them are irrelevant.    (017)

  2. A collection of axioms that define all of the nonlogical
     predicates.  And by nonlogical, that means everything except
     the base operators of and, or, not, some, every, etc.
     Even arithmetic and set theory are part of the ontology.    (018)

This gives a very crisp, very sharp definition.  The supporting tools are 
extremely important, but it is essential to recognize that they are *not* part 
of the ontology.    (019)

John Sowa    (020)


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