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Preliminaries

 

 

*    For the TM in question the tape upon which it operates consists of cells numbered by the integers.

*    At time 0 TM begins operating and scans cell 0.

*    TM operates only between time 0 and the first moment after TM halts. At t < 0 and t > halting time nothing is happening.

*    Recall that any TM is specified by a description consisting of a set of quadruples that represent, in order: the state the machine is in, the symbol read, the action performed, and the new state entered.

There are just 3 types of quadruple.

    1.    (qi, Sj, Sk, qm)    -    rewrite

    2.    (qi, Sj, R, qm)     -    move right

    3.    (qi, Sj, L, qm)     -    move left