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To: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Adam Pease <adampease@xxxxxxxxxxxxx>
Date: Wed, 06 Aug 2003 09:47:08 -0700
Message-id: <>
   I've posted my summary of the reasons we had for our original consensus 
to use first order logic for the ontolog effort.  I've also included the 
text below.    (01)

<http://ontolog.cim3.net/cgi-bin/wiki.pl?Methodology> (bottom of the page)    (02)

Adam    (03)

     * The issue about whether to create a formal ontology in first order 
logic seems to have resurfaced. This is an attempt to summarize our reasons 
for our earlier consensus on using first order logic. (--AdamPease / 
2003-07-31)    (0112)    (04)

           o There were several reasons for the earlier consensus to use 
KIF but foremost among them was the stated purpose of this effort - to 
formalize the content in the UBL, rather than leaving definitions in 
English. If we create the ontology in Protege, we'll be left with stating 
definitions in English. We could state axioms in the comment fields, but 
Protege can't make any use of those axioms, and the tool does not contain 
even the most basic functions like hyperlinking the terms in a pseudo-axiom 
comment. (--AdamPease / 2003-07-31)    (0110)    (05)

           o Protege is a good way to get one's feet wet in ontology. It's 
very easy to use. But it has to be seen as a mere stepping stone to our 
objective. If we linger too long with it, the resulting model will reflect 
Protege's representational capabilities. For those of us who are 
programmers, I'm sure we all will have an anecdote about another programmer 
who "writes Fortran in C" or who "writes C in C++". In order to create code 
that is idiomatic in a given language one needs to write in that language 
at the very least, and make use of its facilities over time, while one 
develops proficiency. (--AdamPease / 2003-07-31)    (0108)    (06)

           o Frame representations have the limitation of not being able to 
represent three-way (or higher number) relations. One has to divide any 
three-way relation into three binary relations with a new "relation ID" 
term. This is very awkward both for representation and reasoning. So 
(between A B C) becomes (between1 A gensym1) (between2 B gensym1) (between3 
C gensym1).    (0114)    (07)

           o Another problem with frames is in the representation of 
negation. In logic we can simply enclose any formula in (not ...) to negate 
it so (likes Mary Bill) can become (not (likes Mary Bill). With a frame 
system we have to create the opposite version of the predicate, say 
"dislikes". That results in doubling the number of relations, since every 
predicate must have an opposite. Maybe that wouldn't be so bad, but one 
would still be limited to negating individual statements, rather than 
abitrary formulas (which a frame system can't represent anyway). The list 
of things a frame system can't handle is extensive.    (0115)    (08)

           o If we stick with a frame representation for long, we'll wind 
up recreating a lot of the content of SUMO, simply because frames can't 
handle the content that already exists.    (0116)    (09)

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