Re: Standardizing FOL
phayes@cs.uiuc.edu
Message-id: <199309231952.AA01295@dante.cs.uiuc.edu>
Reply-To: cg@cs.umn.edu
Date: Thu, 23 Sep 1993 15:02:13 +0000
To: cg@cs.umn.edu, interlingua@isi.edu, sowa@turing.pacss.binghamton.edu
From: phayes@cs.uiuc.edu
X-Sender: phayes@dante.cs.uiuc.edu
Subject: Re: Standardizing FOL
Hi John-
I know I said last word, but Ive got to explain what you still don't seem
to understand.
A semantics isnt (usually) the kind of thing that fits inside a computer:
that's a category mistake, like asking the weight of the letter 'J'. A
semantics is an account of how expressions inside computers might relate to
ways the world might be. Giving a semantics for a logic isnt a process of
programming. Its a process of explaining rigorously (mathematically, if you
like) what the expressions of the logic are supposed to mean. KIF and/or
CG's won't provide me with tools for doing this, and my doing it couldnt
*possibly* have anything other than intellectual effects on anyone else. If
I make a mess of my semantics, nobody but me will ever know unless I try to
publish it. Offering to provide a standard shell to develop semantics
within, like an operating system for software, seems crazy. I know you
aren't, so we must not be understanding one another.
Pat
PS I didnt mean 'hack' to connote bad or careless programming: in the
culture I grew up in, hackers were regarded with awe. I meant only to
distinguish programming or describing a syntactic form (maybe in a
metalanguage) and defining a concept in a logical language. A definition
would, for example, enable you to draw conclusions from assertions using
that syntax.
The reason you can't define lambda-conversion in FOL is that its definition
essentially involves a schema which is not equivalent to any finite set of
first-order expressions (in contrast, for example, with the schema for
equality).
PPS, I PROMISE no more to Internet from me on this. Honestly.
----------------------------------------------------------------------------
Beckman Institute (217)244 1616 office
405 North Mathews Avenue (217)328 3947 or (415)855 9043 home
Urbana, IL. 61801 (217)244 8371 fax
hayes@cs.stanford.edu or Phayes@cs.uiuc.edu