# Models Err

fritz@rodin.wustl.edu (Fritz Lehmann)
Date: Mon, 17 May 93 14:49:11 CDT
From: fritz@rodin.wustl.edu (Fritz Lehmann)
Message-id: <9305171949.AA05837@rodin.wustl.edu>
To: interlingua@ISI.EDU
Subject: Models Err

Sowa argued to Hayes and Schubert that KRep
languages describe a model which is not the real
world itself. One proof that a model is not the
real world itself is its capacity for error. A
Tarskian model can itself be WRONG. It can include
Pat Hayes among U.S. Presidents. (The real world
itself cannot err this way.) The model theoretic
evaluation of a KRep assertion may be flawless and
yield "T"; that alone does not make it true --- in
addition the model must be accurate. Some errors
do not arise in the sentence syntax nor in the
model-theoretic evaluation. The assertion is "true
in the model" but false. Since a model may err, a
model is not the world. Pretty simple, but
evidently disregarded by persons overly steeped in
the technical formal method (and maybe the
notation). A. Sowa is right, and B. accomodating
Sowa's view does no fundamaental harm to KIF
whether he is right or wrong, and may help.
A tiny exception (to digress totally from
current practical KRep issues) is the possibility
that the entire universe (the real one, down to
every electron and below) is generated as a
discrete mathematical structure. This "model"
would necessarily be perfect and incapable of
error. This possibility is explored in the
"combinatorial hierarchy" theory of Discrete
Physics of Noyes, Bastin, Kilmister and other
physicists in Britain and America (this includes
"Program Universe" theory). It is partly based (to
my astonishment) on some theoretical physical
"breakthroughs" by the early AI/linguistics/
mycology theorist A. F. Parker-Rhodes who wrote the
books "Inferential Semantics" and "The Theory of
Indistinguishables".
It would be nice to accomodate both Sowa's
view and the Common LISP reader. It's nice to eat
cake and still have it too. Can this be done?
Yours truly, Fritz Lehmann
25 Seton, Irvine, CA 92715, USA 714-733-0566
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