[Ramesh S. Patil <ramesh@vaxa.isi.edu> : Re: ccodes and rcodes ]

Michael Genesereth <mrg@sunburn.stanford.edu>
Date: Tue, 18 Sep 1990 14:23:51 PDT
From: Michael Genesereth <mrg@sunburn.stanford.edu>
To: interlingua@vaxa.isi.edu
Subject: [Ramesh S. Patil <ramesh@vaxa.isi.edu> : Re: ccodes and rcodes ]
Message-id: <CMM.0.88.653693031.mrg@Sunburn.Stanford.EDU>

Ramesh sent this to me a couple of days ago but did not copy
the group.  He just asked me to nredictribute.  So here we are.


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To: Michael Genesereth <mrg@Sunburn.Stanford.EDU>
Reply-To: ramesh@isi.edu
Subject: Re: ccodes and rcodes 
In-Reply-To: Your message of Fri, 14 Sep 90 12:58:10 -0700.
Date: Mon, 17 Sep 90 09:44:29 PDT
From: Ramesh S. Patil <ramesh@vaxa.isi.edu>

I have a number of comments about the last message sent by Mike.

     (1) As Ramesh mentioned, translating into and out of a ccode 
    requires reasoning of some sort and so the ccode becomes an rcode.

What I was trying to point out is not that Ccode becomes Rcode, but
that if one wishes to explicitly consider the process of translation,
then going from one language to another requires some inference.  More
importantly it brings up the issues of its computational properties,
such as soundness, completeness, and efficiency.  If one considers As
Mike points out, the efficiency is not as major a consideration
because we are willing to separate the cost involved in translation
>From those of the run-time usage of the KR system.  Thus the only
consideration is that it should be practical to translate.  I believe
however, that to insist that a translator be sound and complete (i.e.,
be information preserving) may be too much to expect.  Most languages
for communication do not guarantee that the hearer will get the whole
meaning and only the intended meaning of any message, they only
attempt to minimize misunderstanding.  I believe this is what Bob
MacGregor pointed out when he said:

     (2) As Bob MacGregor pointed out ''implementing'' the ccode is
    difficult or maybe even impossible.

I believe that it is impossible.  But that does not reduce the
importance of communication language nor does it eliminate its
usefulness.  It is possible to be useful even without being sound and
complete.  One way to achieve more accurate understanding between the
speaker and listener is to engage in a dialogue.  Imagine that the
first message is followed by a response in which the listener tells
the speaker some of the inferences it is able to derive based on what
it understood from the initial communication (one must limit this to
mostly what the listener finds surprising or noteworthy to be
concise).  The speaker now can clarify this understanding by pointing
out those inferences that it believes to be legitimate and those it
does not.  In this manner the two can come to a reasonable
understanding of the underlying knowledge being communicated.  This
might be too hard to implement practically, but I present it as an
illustration of how one gets around the imprecision of natural
languages and its translation process that leads to our deep

Finally, I am still puzzled about the need for a statement:

    By the way and IMPORTANT, THERE ARE NO PARADOXES with quote in KIF
    You can write a paradoxical souding sentence, but if you look at
    semantics, there is no contradiction.  The model theoretic
    still gives a perfectly well defned meaning to the entire

If one considers KIF as a Ccode the I don't consider this to be
important.  Most communication languages I know allow one to state
outrageous and even nonsense things in well formed syntactic
statements.  Consider for example the famous sentence due to Chomsky
"Colorless green ideas sleep furiously".  This is a perfectly well
formed sentence in English.  Also to my knowledge the fact that
English can express Russell's paradox does not diminish the usability
of utility of english one bit.  On the contrary if English were
designed carefully to eliminate expression of such statements (or to
banish such thought), we would have never been able to express
Russell's paradox and would therefore have never recognized it.

It is my opinion that any communication language that attempts to
legislate the expression of thought or ideas through the use of syntax
to only those that are logically sound and meaningful inevitably is
ruling out expression of some useful and important ideas.  It is
curtailing our ability to think and thus stymieing future
developments or "freedom of thought and expression".

All this is true of CCODE only.  
 - ramesh