Automata

3. Turing machines are definitely stronger than PDAs (why?). But it is inter- esting to investigate some restricted forms of TMs and see if the restrictions we apply could maintain the computing power of TMs. Here is an example. Consider a restricted TM M, called a one-turn Turing machine, such that during any executions on any input, M makes at most one turn on the tape (i.e., the tape head either always moves to the right, or moves to the left later but never moves to the right again. However, the tape head could stay at any moment.) Show (describe) that languages accepted by one-turn Turing machines are context-free