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From: breuel@h-sc1.UUCP (thomas breuel)
Newsgroups: net.philosophy,net.math,net.physics
Subject: Re: Mind as Turing Machine (a few illuminating comments)
Message-ID: <735@h-sc1.UUCP>
Date: Sat, 9-Nov-85 00:17:23 EST
Article-I.D.: h-sc1.735
Posted: Sat Nov  9 00:17:23 1985
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Below are the answers to two questions that 'biep@klipper.UUCP'
asked. Altogether, you can make many comparisons between the
brain and Turing machines, but such comparisons
will not tell you much about either theoretical or practical
limitations of the human brain.

						Thomas.

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** Why is time complexity not a useful measure for comparing
   a Turing machine with a real life architecture?

Turing machines are very nice devices for theoretical considerations.
In a sense, they give the most believable and strict measure of
computational complexity. For real life architectures, the theoretical
benefits of a Turing machine are unimportant. You can't, for example
do accesses to data on a Turing machine in less than O(n), whereas
in real life, even on a serial architecture, you can do them
in essentially constant time.

** Can you define 'Turing equivalent'?

Something is Turing equivalent if it can simulate a Turing machine.
Since a Turing machine does not have a limit on the amount of
information that it can store, anything that can simulate
a Turing machine can also not have a limit on the amount of
information that it can store. The human mind probably has such
a limit (judging from its architecture). Therefore,
the human mind is probably not Turing equivalent.