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From: edwards@uwmacc.UUCP (mark edwards)
Newsgroups: net.philosophy,net.math,net.physics
Subject: Re: Mind as Turing Machine: a proof *and* a disproof!
Message-ID: <1637@uwmacc.UUCP>
Date: Mon, 4-Nov-85 09:15:44 EST
Article-I.D.: uwmacc.1637
Posted: Mon Nov  4 09:15:44 1985
Date-Received: Tue, 5-Nov-85 07:20:09 EST
References: <1996@umcp-cs.UUCP> <667@hwcs.UUCP> <2031@umcp-cs.UUCP> <509@klipper.UUCP> <1096@jhunix.UUCP>
Reply-To: edwards@uwmacc.UUCP (mark edwards)
Organization: UWisconsin-Madison Academic Comp Center
Lines: 42
Keywords: minds, Turing machines
Xref: linus net.philosophy:2760 net.math:2115 net.physics:3238

In article <1096@jhunix.UUCP> ins_apmj@jhunix.ARPA (Patrick M Juola) writes:
>In article <509@klipper.UUCP> biep@klipper.UUCP (J. A. "Biep" Durieux) writes:
>>	                                        Psycholinguistics has
>>	found that humans can search their memory in < log n time, n
>>	being the number of items. Turing machines clearly can not do
>>	better than order n time. Proof that humans are not Turing machines.
>
>	I'm sure that a Turing machine can search its memory faster than order
>n : all it would have to do is store the stuff in its memory in some sort of 
>order.  I'm thinking specifically of the structure called a binary tree, where
>everything in the right sub-tree is > the root and the left is < the root.
>Program the machine to start at some designated root (call it position 1) on
>the tape.  If the item to be searched for is < position n, shift left (for 
>example) to position n*2.  If the item is >, shift left to position n*2+1.
>This, on the average, will find any item in memory in log(base 2)n comparisons,
>and you've still got an infinite amount of tape to the right for storage of
>other items.
>						Pat Juola


 While your premise is true for simple data forms, it breaks done as
 the complexity goes up. Namely semantic concepts vs a simple binary
 number search.

 This is not to say that I support the log n  vs  n search times. There
 are many other attributes on which to search. One such would be a 
 picture (A picture is worth a thousand words). This is not to say that
 a turing machine can not do it, only it can not do it today.(tomorrow ?)

The brain has a highly parallel interconnected architecture. Each neuron
has 100 to 10000 other neurons connected to it. This means after 3 cycles
using the low figure 1000000 neurons can be activated (in parallel). While
the computer will have only 3 things done (what ever that means). Granted
that the computer is much faster (100 to 1000 x ?) th brain still has
it beat because of parallelism. Scientific America says that there 
are 10 to the 10 or 11 neurons in the brain. If only a tenth of these
are used the brain still has a large magnitude more memory then a
modern processor has.

mark
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