منابع مشابه
Simulation of Two-Way Pushdown Automata Revisited
The linear-time simulation of 2-way deterministic pushdown automata (2DPDA) by the Cook and Jones constructions is revisited. Following the semantics-based approach by Jones, an interpreter is given which, when extended with random-access memory, performs a linear-time simulation of 2DPDA. The recursive interpreter works without the dump list of the original constructions, which makes Cook’s in...
متن کاملTwo-sided Pushdown Automata over Free Groups
In the two-sided pushdown automata discussed in this paper, their two-sided pushdowns are introduced over free groups rather than free monoids. It is demonstrated that these automata with pushdowns introduced in this way characterize the family of recursively enumerable languages.
متن کاملTwo-Way Two-Tape Automata
In this article we consider two-way two-tape (alternating) automata accepting pairs of words and we study some closure properties of this model. Our main result is that such alternating automata are not closed under complementation for non-unary alphabets. This improves a similar result of Kari and Moore for picture languages. We also show that these deterministic, non-deterministic and alterna...
متن کاملTropical Two-Way Automata
In this paper we study two-way min-plus automata. We prove that two-way distance automata are equivalent to one-way distance automata. In the second part of the paper we show that, with general min-plus semirings, it is decidable whether every accepted word has a weight different from −∞ and that, in contrast, it is undecidable whether there exists a word accepted with a weight different from −∞.
متن کاملDescriptional Complexity of Two-Way Pushdown Automata with Restricted Head Reversals
Two-way nondeterministic pushdown automata (2PDA) are classical nondeterministic pushdown automata (PDA) enhanced with two-way motion of the input head. In this paper, the subclass of 2PDA accepting bounded languages and making at most a constant number of input head turns is studied with respect to descriptional complexity aspects. In particular, the effect of reducing the number of pushdown r...
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ژورنال
عنوان ژورنال: Information and Control
سال: 1967
ISSN: 0019-9958
DOI: 10.1016/s0019-9958(67)90369-5