# Automata Theory Questions and Answers – Multitape Turing Machines

This set of Automata Theory Multiple Choice Questions & Answers (MCQs) focuses on “Multitape Turing Machines”.

1. A turing machine with several tapes in known as:
a) Multi-tape turing machine
b) Poly-tape turing maching
c) Universal turing machine
d) All of the mentioned

Explanation: A multitape turing machine is an ordinary turing machine with multiple tapes. Each tape has its own head to control the read and write.

2. A multitape turing machine is ________ powerful than a single tape turing machine.
a) more
b) less
c) equal
d) none of the mentioned

Explanation: The multitape turing machine model seems much powerful than the single tape model, but any multi tape machine, no matter how many tapes, can be simulated by single taped TM.

3. In what ratio, more computation time is needed to simulate multitape turing machines using single tape turing machines?
a) doubly
b) triple
d) none of the mentioned

Explanation: Thus, multitape turing machines cannot calculate any more functions than single tape machines.

4. Which of the following is true for two stack turing machines?
b) two storage tapes
c) one read only input & two storage tapes
d) None of the mentioned

Explanation: Two-stack Turing machines have a read-only input and two storage tapes. If a head moves left on either tape a blank is printed on that tape, but one symbol from a “library” can be printed.

5. Which of the following is not a Non deterministic turing machine?
a) Alternating Turing machine
b) Probabalistic Turing machine
d) None of the mentioned

Explanation: A read only turing machine or 2 way deterministic finite automaton is a class of model of computability that behaves like a turing machine, and can move in both directions across input, except cannot write to its input tape.

6. Which of the turing machines have existential and universal states?
a) Alternating Turing machine
b) Probalistic Turing machine
d) None of the mentioned

Explanation: ATM is divide into two sets: an existential state is accepting if some transitions leads to an accepting state; an universal state is accepting if every transition leads to an accepting state.

7. Which of the following is false for Quantum Turing machine?
a) Abstract machine
b) Any quantum algorithm can be expressed formally as a particular quantum turing machine
c) Gives a solution to ‘Is a universal quantum computer sufficient’
d) None of the mentioned

Explanation: ‘Is a universal quantum computer sufficient’ is one of the unsolved problem from physics.

8. A deterministic turing machine is:
a) ambiguous turing machine
b) unambiguous turing machine
c) non-deterministic
d) none of the mentioned

Explanation: A deterministic turing machine is unambiguous and for every input, there is exactly one operation possible. It is a subset of non-deterministic Turing machines.

9. Which of the following is true about Turing’s a-machine?
a) a stands for automatic
b) left ended, right end-infinite
c) finite number of tape symbols were allowed
d) all of the mentioned

Explanation: Turings a- machine or automatic machine was left ended,right end infinite.Any of finite number of tape symbols were allowed and the 5 tuples were not in order.

10. Which of the following is a multi tape turing machine?
a) Post turing Machine
b) Wang-B Machine
c) Oblivious turing Machine
d) All of the mentioned

Explanation: An oblivious turing machine where movements of various heads are fixed functions of time, independent of the input. Pippenger and Fischer showed that any computation that can be performed by a multi-tape Turing machine in n steps can be performed by an oblivious two-tape Turing machine in O(n log n) steps.

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