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Re: [ontolog-forum] Role of definitions (Remember the poor human)

To: "John F. Sowa" <sowa@xxxxxxxxxxx>
Cc: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Wed, 14 Feb 2007 13:58:29 -0600
Message-id: <p06230909c1f91705bbb9@[]>
>We (and many others) have been debating various issues about
>ontology for multiple decades without reaching any kind of
>agreement.    (01)

Oh, I think that is slightly unfair. We have managed to create RDF, 
OWL, CL and more recently IKL and soon SPARQL. This represents a 
considerable achievement, IMO.    (02)

If you mean agreement about actual ontological content, no of course 
we have not reached agreement, and we never will. Neither will any 
reasonably large group of people. People do all think in the same way.    (03)

>  The voluminous archives of the SUO mailing list
>(from around 2000 AD), the SRKB mailing list (1991 AD), and
>several others attest to that fact.
>If people who have seriously thought about the issues don't
>make some recommendations, somebody who hasn't thought about
>them will write a tool or language that becomes widely used,
>and we are going to be forced to live with it.    (04)

Nonsense. Take OWL for example. There are many, many possible OWL 
tools, even OWL reasoners. Adopting OWL as a standard does not 
constrain this. (I am not here endorsing OWL, only making a general 
observation.)    (05)

>>  First, we would have to decide what the right set of "levels"
>>  should be. Should there be 5 of them, as you suggest? Or 3, as
>>  Cyc has chosen? Four? Twelve? Perhaps the whole idea of a total
>>  order is wrong: can the levels be *partially* ordered? (There's
>>  a PhD thesis lurking there.)..........
>Not just lurking.  In my KR book, I recommended partial orderings
>(note plural)    (06)

I note it. Sigh. That is REALLY going to help with interoperability.    (07)

>  based on Benjamin Grosof's dissertation of 1992.
>  1. The importance of levels of entrenchment should be recognized.
>  2. At the very minimum, there should be three levels:  (1) the
>     statements that specify the type hierarchy, (2) other axioms
>     (called "constraints"), (3) ordinary factual assertions.    (08)

Already I disagree. WHY is the type hierarchy more entrenched than 
anything else? Such hierarchies do change, sometimes quite quickly. 
For example, an ontology might be used to represent a parts catalog, 
organized into various categories. Such categories can be revised 
quite often.    (09)

>  3. Other levels should be optional, any number should be permitted,
>     and they must be partially ordered (with those three as part
>     of the ordering).    (010)

What exactly is the partial order? That is, what does it mean? Must 
my partial order be consistent with yours? What if we disagree? Does 
having our levels explicit in this way help us resolve any conceptual 
disagreements we might have had? AFAIKS, it simply produces more ways 
for us to disagree.    (011)

>  4. As Kathy has emphasized, probabilistic statements are extremely
>     important for many domains, especially medicine.  They can be
>     accommodated by one or more levels that are below the facts
>     in entrenchment.    (012)

Hmm, that is an extremely doubtful claim.    (013)

>I certainly agree that more applied research would be valuable,
>but an enormous amount of research *and* practice has already
>been done over the past 30 years.  We should recognize it and
>make some recommendations for how it should be accommodated.    (014)

The best way for a standards-setting body or organization to 
accommodate something is to ignore it. If we say ANYTHING about this 
stuff, we are interfering with someone's ability to experiment. 
Unless we can say something that (a) is widely agreed throughout a 
large community and (b) requires uniformity of use in order to 
achieve interoperability of some kind, then our only responsible 
action is to keep silent about it. I strongly suggest that neither of 
these criteria are met by this talk of entrenchment levels.    (015)

Pat    (016)

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