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Parallelism in random access machines

Steven Fortune, +1 more
- pp 114-118
TLDR
A model of computation based on random access machines operating in parallel and sharing a common memory is presented and can accept in polynomial time exactly the sets accepted by nondeterministic exponential time bounded Turing machines.
Abstract
A model of computation based on random access machines operating in parallel and sharing a common memory is presented. The computational power of this model is related to that of traditional models. In particular, deterministic parallel RAM's can accept in polynomial time exactly the sets accepted by polynomial tape bounded Turing machines; nondeterministic RAM's can accept in polynomial time exactly the sets accepted by nondeterministic exponential time bounded Turing machines. Similar results hold for other classes. The effect of limiting the size of the common memory is also considered.

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Citations
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References
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Journal ArticleDOI

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Journal ArticleDOI

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TL;DR: The parallel arithmetic complexities of matrix inversion, solving systems of linear equations, computing determinants and computing the characteristic polynomial of a matrix are shown to have the same growth rate.
Journal ArticleDOI

Time bounded random access machines

TL;DR: It is proved that a T(n) time-bounded Turing machine can be simulated by an O(T(n).l( t(n), l(n))) timebounded RAM, and that a L( n), a fixed program, can be simulate by a Turing machine whose execution time is bounded by (T( n))^3 if l( n) is constant, or (T (n) is logarithmic.
Proceedings ArticleDOI

Time-bounded random access machines

TL;DR: This paper introduces a formal model for random access computers and argues that the model is a good one to use in the theory of computational complexity and shows the existence of a time complexity hierarchy which is finer than any standard abstract computer model.
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