Subject: Davis on Turing Machines
From: "William J. Rapaport" <rapaport@buffalo.edu>
Date: Thu, 4 Feb 2010 10:34:06 -0500 (EST)

A student writes:
"I'm reading the Davis paper and I'm having difficulty with the portion
describing Turing's simplification of the 'computer's' behavior. When
he lists the atomic steps the 1st one states:

"1. a change of one symbol in one of the B 'observed' squares (changes
of more than one symbol can always be reduced to successive changes of
a single symbol)

"In that latter part about successive changes, does he mean remaining
in the B "observed" square and making successive changes to the symbol
without moving to another B "observed" square?"

Reply:  
I think so. When we go through Turing's paper in class, we can
talk more about this. Don't worry about the details of how Turing
machines work at this stage; just read Davis for the history.