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A set of equivalences is established among cellular automata, iterative acceptors, and linear-bounded automata. However, cellular automata are shown to be inherently faster than iterative acceptors. Many positive results are presented to indicate that the context-free languages can, perhaps, be accepted in time n and space n by cellular automata.
The aim of this paper is not the establishment of new results, but the understanding, from a machine theoretic point of view, of results originally arrived at by algebraic means. A new criterion for series parallel irreducibility is given which makes no reference to underlying semigroups but involves only series parallel operations. Also, the irreducibility of prime counter machines is established...
Two classes of restricted top down parsing algorithms using backtrack are considered. We show that the smaller class recognizes all deterministic context free languages, and that both classes can be simulated in linear time on a random access machine. Certain generalizations of these parsing algorithms are shown equivalent to the larger class. Finally, some decision and closure properties of the classes...
The computational power of 2-way pushdown automata with m additional counters (called mC-PDA) is investigated. It is shown that any multi-tape Turingmachine (with a two-way input tape) which accepts within time T(n), where n is the input length, can be simulated by a 3C-PDA whose counters are bounded by T(n) and that any such Turing machine can also be simulated by a 2C-PDA whose counters are bounded...
A model for parallel computation called a schema is presented. This model is similar to that presented in the recent work of Karp and Miller2. Section 1 presents a description of the model, and some results on the characterization of computations within it. Section 2 summarizes some results on determinacy and equivalence. Section 3 presents a formalization of the property of maximal parallelism in...
We study the effect of program structure on computational efficiency in a class of abstract languages which model actual high-level numerical programming languages (like ALGOL). The results have bearing on programming technique (the use of go to statements), and they yield interesting facts about Blum's speed-up theorem for subrecursive computational complexity.
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