From newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!rpi!bu.edu!BUPHY0.BU.EDU!leao Mon May 25 14:05:55 EDT 1992
Article 5709 of comp.ai.philosophy:
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>From: leao@BUPHY0.BU.EDU (Joao Leao)
Newsgroups: comp.ai.philosophy
Subject: Re: penrose
Message-ID: <86344@bu.edu>
Date: 17 May 92 15:58:26 GMT
References: <2524@ucl-cs.uucp> <1992May1.025230.8835@news.media.mit.edu> <1992May6.220605.26774@unixg.ubc.ca> <1992May8.115737.28474@nuscc.nus.sg>
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In article <1992May8.115737.28474@nuscc.nus.sg>, smoliar@hilbert.iss.nus.sg (stephen smoliar) writes:
|> In article <1992May6.220605.26774@unixg.ubc.ca> ramsay@unixg.ubc.ca (Keith
|> Ramsay) writes:
|> >In article <1992May1.025230.8835@news.media.mit.edu>
|> >minsky@media.mit.edu (Marvin Minsky) writes:
|> >> The math seems generally OK, but the stuff on universal Turing machines
|> >>seems
|> >>amateurish.  He either did not know, or neglected to point out that
|> >>there are known to be very small Universal Turing Machines (e.g, 4
|> >>symbols, 7 states).  
|> >
|> >Is there some special significance to this fact (so that one would
|> >make a special point of including it)?
|> >
|> One special point is that a Universal Turing Machine is not a very big "thing."
|> For example, it has fewer bits than the human genetic code.  I think it is very
|> important to realize that universal computation does not require some enormous
|> and elaborately convoluted structure.  It is simple enough that it could
|> probably arise by selection from a reasonably sized population of diverse
|> alternatives.
|> -- 
|> Stephen W. Smoliar; Institute of Systems Science
|> National University of Singapore; Heng Mui Keng Terrace
|> Kent Ridge, SINGAPORE 0511
|> Internet:  smoliar@iss.nus.sg


This is an interesting and suggestive point but quite misleading because it fails to aknowledge the fact that Turing Machines do not "evolve" in any plausible sense of the word: they are not self-reproducing automata! It is thus close to meaningless to cl
aim that UTMs are simple enough ("shallow" is a
better term, actually) to "have arisen by selection from a reasonably sized population of diverse alternatives". In the absence of a mechanism that 
sustains uniformity/variety it makes no sense to talk about a "population
of alternatives". Such mechanism cannot by itself arise in the absence of
some form of reproduction or of an algorithm that generates all the possible
"alternatives". In all probability this generating algorithm will need to be
an UTM which begs the question. This is even before you need to consider the
alternatives for selection...

Joao Pedro Leao (Artificial Iconoclast and Director of Computer Resources
Artificial Physics Lab * Boston University - Physics Dept. Boston MA 02215)
 	leao@buphy.bu.edu | leao@buphyc.bitnet | BUPHYC::LEAO 
"Well I am sitting here in Tahiti/ I am laying in the sun and sipping a...
...chartreuse tropical drink!/ and I say: I know those Bermuda shorts!..."
									


