CS 208: Computing Theory. Assoc. Prof. Dr. Brahim Hnich Faculty of Computer Sciences Izmir University of Economics. Computability Theory. Turing Machines. TMs. We introduce the most powerful of the automata we will study: Turing Machines (TMs)
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Assoc. Prof. Dr. Brahim Hnich
Faculty of Computer Sciences
Izmir University of Economics
Turing Machines
State
control
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A Turing Machine is a theoretical computer consisting of a tape
of infinite length and a readwrite head which can move left and
right across the tape.
aa,R
ba,R
aa,R means TM reads the symbol a, it replaces it with a
and moves head to right
This TM when reading an a will move right one square stays in the
same start state. When it scans a b, it will change this symbol to an
a and go into the other state (accept state).
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ξ(q,a) = (r,b,L) means
in state q where head reads tape symbol a
the machine overwrites a with b
enters state r
move the head left
Turing Machines
definition
examples
Enumerable/decidable
languages
definition
Next: Decidability Theory