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Subject: 
RE: recursion (was RE: Would-be hacker queries.) (fwd)
Newsgroups: 
lugnet.robotics
Date: 
Thu, 13 May 1999 15:11:57 GMT
Original-From: 
Jim Choate <ravage@EINSTEIN#ihatespam#.ssz.com>
Viewed: 
1094 times
  
----- Forwarded message from Blake Winton -----

From: Blake Winton <Blake.Winton@pcdocs.com>
Subject: RE: recursion (was RE: Would-be hacker queries.)
Date: Thu, 13 May 1999 11:40:10 -0400

(From http://www.google.com/ searching for "The Ackermann Function")
The url to a description of Ackermann's function:
http://public.logica.com/~stepneys/cyc/a/ackermnn.htm

An excerpt from that page:
Ackermann's function, while Turing computable, grows faster than any
primitive recursive function.

This means that any given Ackermann number can be computed by a machine
with
a finite number of states, and an infinite tape of places to store
values.

Note that the Turing machine isn't a recursive machine.  (i.e. It can't
call
another Turing machine, and get the return value.)  Therefore, anything
which
can be computed by a Turing machine can be computed iteratively.

----- End of forwarded message from Blake Winton -----

This issue of a Turing machine calling a Turing machine for recursion is
specious.

A Turing machine only needs to copy a sub-set of its current dataset out to
tape and then, using the same program, jump to it. It then does the same
thing all over again until it reaches a termination condition.

You never need more than 1 Turing machine, it can emulate multiple Turing
machines as needed.

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Message has 1 Reply:
  Re: recursion (was RE: Would-be hacker queries.) (fwd)
 
(...) How would it jump back to the original tape? -Paul (pspeed@progeeks.com) -- Did you check the web site first?: (URL) (25 years ago, 13-May-99, to lugnet.robotics)

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