Re: Turing Machines and Physical Computation

From: Stephen Harris (cyberguard1048-usenet_at_yahoo.com)
Date: 11/22/04 

Date: Mon, 22 Nov 2004 07:07:11 GMT

"JXStern" <JXSternChangeX2R@gte.net> wrote in message
news:v3n2q0tp4d3pelduh327ncs8tnflfdr7gl@4ax.com...
> On Mon, 22 Nov 2004 01:48:39 GMT, "Stephen Harris"
> <cyberguard1048-usenet@yahoo.com> wrote:
>>> I'm a big fan of SEP, but I believe the idealist interpretation they
>>> give Turing machines in several articles is inconsistent with what
>>> Turing wrote, and inconsistent with what he wrote about.
>>
>>I'm not sure what SEP stands for.
>
> The Stanford Encylopedia of Philosophy that you gave several URLs
> from.
>
> J.
>

http://www.alanturing.net/turing_archive/pages/Reference%20Articles/What%20is%20a%20Turing%20Machine.html#head
by B.J. (Jack) Copeland

"Commercially available computers are hard-wired to perform primitive
operations considerably more sophisticated than those of a Turing machine
--add, multiply, decrement, store-at-address, branch, and so forth. The
precise constitution of the list of primitives varies from manufacturer to
manufacturer. It is a remarkable fact that none of these computers can outdo
a Turing machine. Despite the Turing machine's austere simplicity, it is
capable of computing anything that any computer on the market can compute.

Indeed, since it is an abstract or notional machine, a Turing machine can
compute more than any physical computer. This is because

(1) the physical computer has access to only a bounded amount of memory,
and
(2) the physical computer's speed of operation is limited by various
real-world constraints.

It is sometimes said, incorrectly, that a Turing machine is necessarily
slow, since the head is continually shuffling backwards and forwards,
one square at a time, along a tape of unbounded length. But since a
Turing machine is an idealised device, it has no real-world constraints
on its speed of operation."

Copeland's qualification and publications:
http://www.phil.canterbury.ac.nz/people/copeland.shtml
http://www.phil.canterbury.ac.nz/personal_pages/jack_copeland/publist.shtml#articles

http://www.phil.canterbury.ac.nz/people/copeland.shtml Abstract:
"Fuzzy logic extends deductive methods to situations in which the
information available may be only partly or approximately true. Fuzzy logic
has often been championed as a logic of vague terms, and it does indeed
provide an intuitive analysis of what goes wrong in Sorites reasoning."

Distinguishably,
Stephen

Relevant Pages

  • Re: Turing Machines and Physical Computation
    ... operations considerably more sophisticated than those of a Turing machine ... precise constitution of the list of primitives varies from manufacturer to ... the physical computer has access to only a bounded amount of memory, ... Turing machine is an idealised device, it has no real-world constraints ...
    (sci.math)
  • Re: Turing Machines and Physical Computation
    ... >> The Stanford Encylopedia of Philosophy that you gave several URLs ... > operations considerably more sophisticated than those of a Turing machine ... > precise constitution of the list of primitives varies from manufacturer to ...
    (sci.math)
  • Re: Turing Machines and Physical Computation
    ... >> The Stanford Encylopedia of Philosophy that you gave several URLs ... > operations considerably more sophisticated than those of a Turing machine ... > precise constitution of the list of primitives varies from manufacturer to ...
    (comp.theory)
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