The tm program simulates deterministic Turing machines.  It performs
absolutely no error checking and provides absolutely no help
whatsoever.

You might need to change the line at the top of the tm program
from #!/usr/local/bin/perl to #!/usr/bin/perl.

The tm program can be invoked by:

	./tm tmfile input

where tmfile is a file that specifies the Turing machine and input is
the input to the Turing machine.  For example, here is the file mab:

	q0 c q0 c R
	q0 a q1 c R
	q0 b q2 c R
	q0 _ accept _ L
	q1 a q1 a R
	q1 b q3 c L
	q1 c q1 c R
	q2 a q3 c L
	q2 b q2 b R
	q2 c q2 c R
	q3 a q3 a L
	q3 b q3 b L
	q3 c q3 c L
	q3 _ q0 _ R

Each line specifies a transition of the Turing machine, e.g., the
first line "q0 c q0 c R" specifies that if the Turing machine is in
state q0 and is currently reading a c, then it stays in state q0,
writes a c, and moves one square to the right.  The second line
"q0 a q1 c R" specifies that if the Turing machine is in state q0 and
is currently reading an a, then it goes to state q1, writes a c, and
moves one square to the right.

The initial state is assumed to be q0.  The _ character is used to
denote a blank.

Here is what should happen when you invoke "./tm mab ba":

          q0
          |
        __ba__

           q2
           |
        __ca__

          q3
          |
        __cc__

         q3
         |
        __cc__

          q0
          |
        __cc__

           q0
           |
        __cc__

            q0
            |
        __cc__

           accept
           |
        __cc__

Each group of 3 lines displays a configuration of the Turing machine,
with the state on the first line.  The second line indicates the
current position of the read-write head.  The third line displays the
current string on the tape.  Blanks are displayed as underscores.  You
need to enter a return for each configuration.

There are three example Turing machines in the tarfile.

mab: Input alphabet is {a,b}. This Turing machine will end up in state
accept if the number of a's equals the number of b's.

m2x: Input alphabet is {1}.  This Turing machine will double the
number of 1's in the input, ending up in state qf.

mincr: Input alphabet is {0,1}.  This Turing machine will increment
the binary number, ending up in state qf.

Tom Bylander
bylander@cs.utsa.edu