# Two-Tape Simulation of Multitape Turing Machines

@article{Hennie1966TwoTapeSO, title={Two-Tape Simulation of Multitape Turing Machines}, author={F. C. Hennie and Richard Edwin Stearns}, journal={J. ACM}, year={1966}, volume={13}, pages={533-546} }

It has long been known that increasing the number of tapes used by a Turing machine does not provide the ability to compute any new functions. On the other hand, the use of extra tapes does make it possible to speed up the computation of certain functions. It is known that a square factor is sometimes required for a one-tape machine to behave as a two-tape machine and that a square factor is always sufficient.
The purpose of this paper is to show that, if a given function requires computation…

## 271 Citations

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It is shown that the structure of reversible time complexity classes mirrors that of irreversible complexity theory, with a similar hierarchy, and that identical results hold for multitape RTMs.

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Theorems are proved concerning the hierarchy of complexity classes of binary sequences which is obtained by bounding simultaneously both the time T( n) and the amount of tape L(n) which a Tnring machine may use to compute its output sequence; among these is a result on the maximum increase necessary in the time and tape bounding functions.

### Computational Complexity of One-Tape Turing Machine Computations

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The context-sensitive languages cannot be recognized in linear time by deterministic multitape Turing machines, and are strictly contained in the class of languages recognized by Turing machines of tape complexity.

### Multi-tape and infinite-state automata—a survey

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A survey of machines which are more powerful than finite automata and less powerful than general Turing machines is presented. It is felt that the machines in this category are as closely related to…

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It is obtained that there is a language L d not accepted by any polynomial-time deterministic Turing machines but accepted by a nondeterministic Turing machine working within O ( n k ) for any k ∈ N 1 .

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