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Article 5351 of comp.ai.philosophy:
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>From: minsky@media.mit.edu (Marvin Minsky)
Subject: Re: penrose
Message-ID: <1992May1.025230.8835@news.media.mit.edu>
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References: <2524@ucl-cs.uucp>
Date: Fri, 1 May 1992 02:52:30 GMT
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In article <2524@ucl-cs.uucp> G.Joly@cs.ucl.ac.uk (Gordon Joly) writes:
>
>>> His mathematics, per se, is excellent.
>He was a geometer first. His early work was in projective geometry.
>Heard of Penrose tiles? The aperiodic tiling of the plane.
>And his work on (aperiodic?) crystals has proved prophetic.
>That triangle on the front of GEB...

  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).  


  So far as I can see, Penrose's discussion about Godel's theorem
depends on making peculiar assumptions about (1) that humans have
magical abilities to recognize mathematical truths and (2) that the
Turing machines aren't allowed to generate new Turing machines that
use different sets of axioms.

  As for aperiodic tiling, these were first discovered by Hao Wang and
his students; Penrose may have discovered smaller examples.

  In my view the discussions about AI and consciousness in his book
are virtually vacuous; the parts that seem correct, as some wit said,


