Variation of Turing Machine

Prerequisite – Turing Machine

1. Multiple track Turing Machine:

  • A k-tack Turing machine(for some k>0) has k-tracks and one R/W head that reads and writes all of them one by one.
  • A k-track Turing Machine can be simulated by a single track Turing machine

2. Two-way infinite Tape Turing Machine:

  • Infinite tape of two-way infinite tape Turing machine is unbounded in both directions left and right.
  • Two-way infinite tape Turing machine can be simulated by one-way infinite Turing machine(standard Turing machine).

3. Multi-tape Turing Machine:

  • It has multiple tapes and controlled by a single head.
  • The Multi-tape Turing machine is different from k-track Turing machine but expressive power is same.
  • Multi-tape Turing machine can be simulated by single-tape Turing machine.

4. Multi-tape Multi-head Turing Machine:

  • The multi-tape Turing machine has multiple tapes and multiple heads
  • Each tape controlled by separate head
  • Multi-Tape Multi-head Turing machine can be simulated by standard Turing machine.

5. Multi-dimensional Tape Turing Machine:

  • It has multi-dimensional tape where head can move any direction that is left, right, up or down.
  • Multi dimensional tape Turing machine can be simulated by one-dimensional Turing machine

6. Multi-head Turing Machine:

  • A multi-head Turing machine contain two or more heads to read the symbols on the same tape.
  • In one step all the heads sense the scanned symbols and move or write independently.
  • Multi-head Turing machine can be simulated by single head Turing machine.

7. Non-deterministic Turing Machine:

  • A non-deterministic Turing machine has a single, one way infinite tape.
  • For a given state and input symbol has atleast one choice to move (finite number of choices for the next move), each choice several choices of path that it might follow for a given input string.
  • A non-deterministic Turing machine is equivalent to deterministic Turing machine.

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