Models Err (Fritz Lehmann)
Date: Mon, 17 May 93 14:49:11 CDT
From: (Fritz Lehmann)
Message-id: <>
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 

	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