Searle

John K Clark (johnkc@well.com)
Fri, 13 Feb 1998 22:59:54 -0800 (PST)


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On Fri, 13 Feb 1998 Hara Ra <harara@shamanics.com> Wrote:

>Nits:
>1) We are not Turing machines, only possibly equivalent to them.

What's the difference?

>2) With a finite tape, please...

A tape of indeterminate length is good enough, a Turing machine would only
need an infinite tape if it was to perform an infinite number of calculations.
That's not allowed in most models because the tape or the head would have to
move at infinite speed, but more important, the resulting hypothetical
machine would be able to do virtually anything and so render it almost
useless in helping us understand how real computation works, and that's the
reason Turing invented his machine in the first place.

John K Clark johnkc@well.com

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