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Topic: Feedback in Turing Machines
Replies: 17   Last Post: May 29, 2013 12:36 AM

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Graham Cooper

Posts: 4,237
Registered: 5/20/10
Re: Feedback in Turing Machines
Posted: May 28, 2013 7:28 PM
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On May 29, 5:04 am, apoorv <skj...@gmail.com> wrote:
> On May 28, 6:29 pm, apoorv <skj...@gmail.com> wrote:
>
>
>
>
>
>
>

> > On May 27, 10:37 am, Graham Cooper <grahamcoop...@gmail.com> wrote:
>
> > > On May 27, 2:32 pm, William Elliot <ma...@panix.com> wrote:
>
> > > > On Sun, 26 May 2013, apoorv wrote:
> > > > > On May 27, 8:13 am, William Elliot <ma...@panix.com> wrote:
> > > > > > On Sat, 25 May 2013, apoorv wrote:
> > > > > > > Is there some study on situation where the output from a TM at time T is
> > > > > > > fed back so that the total input at time T+1 is some function of output
> > > > > > > at time T and external input at time T+1.?

>
> > > > > > So imput is on the right and out on the left and when done at time t, move
> > > > > > the output to the right of the tape and start again.

>
> > > > > > Time t+1 begins the new output from the old output. You get to wait until
> > > > > > time t2 for the full second output.

>
> > > > > The external input and the output have to be combined
> > > > > So the second TM is necessary?

>
> > > > Input 1 on the right side, gives output 1 on the left side.
> > > > When done, imput 1 is erased and output 1 copied to the right side
> > > > where it's now imput 2.  Imput 2 is used by the same machine
> > > > to produce output 2 on the left side.

>
> > > Starting left and finishing right is just a convention.
>
> > > n=1
> > > TMn - Start left, finish left, signal halt.
> > > n++
> > > repeat

>
> > > Seems there is never an output.
>
> > > Herc
> > > --www.phpPROLOG.com

>
> > Eliot's post ,which appears to be deleted, showed that a single
> > TM , could implement feedback. However, if we put the added
> > Requirement that the input at time t is processed with delay not
> > exceeding
> > A fixed time t0, then two TM s appear necessary .
> > -Apoorv

>
> An interesting thought. Since the brain uses
> Almost real time feedback ,if at all it is digital
> nature, then we should look for not one but two
> Processors. Processor 1 receives the external input
> And the output from processor 2 ,(this is also the
> Final output). The combined input then goes to processor
> 2, which generates the final output.
> A flow diagram -:
>
> External input-------->Processor 1-->-
>   (sensory).       |                 |
>                   /\.                |Total input
>          Fin output internal feedback|
>                   |minimal lag       |
> Final output<----------Processor2--<--
> (motor )
>
> -Apoorv


Anything this does can be Emulated by 1 TM.

This is all modelled much more accurately using L-->R
reduction grammars with terminal and non-terminal (final output)
symbols.

SEE EBNF Grammar.

I have an example of USER INPUT parsing with EBNF
that defines the PROLOG SYNTAX at

http://phpprolog.com/help.php

Rules 1-7


Herc



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