Topic
Pushdown automaton
About: Pushdown automaton is a research topic. Over the lifetime, 1868 publications have been published within this topic receiving 35399 citations.
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TL;DR: State-alternating context-free grammars are introduced, and the language classes obtained from them are compared to the classes of the Chomsky hierarchy as well as to some well-known complexity classes.
17 citations
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05 Jul 1993TL;DR: It is shown that nondeterministic two-way reversal-bounded multicounter machines are effectively equivalent to finite automata on unary languages, and hence their emptiness, containment, and equivalence problems are decidable also.
Abstract: We look at some decision questions concerning two-way counter machines and obtain the strongest decidable results to date concerning these machines. In particular, we show that the emptiness, containment, and equivalence problems are decidable for two-way counter machines whose counter is reversal-bounded (i.e., the counter alternates between increasing and decreasing modes at most a fixed number of times). We use this result to give a simpler proof of a recent result that the emptiness, containment, and equivalence problems for two-way reversal-bounded pushdown automata accepting bounded languages (i.e., subsets of w 1 * ... w k * for some nonnull words w1,...,wk) are decidable. Other applications concern decision questions about simple programs. Finally, we show that nondeterministic two-way reversal-bounded multicounter machines are effectively equivalent to finite automata on unary languages, and hence their emptiness, containment, and equivalence problems are decidable also.
17 citations
31 May 1963
TL;DR: In this report sever al special cases are studied in which the unique determination of the behavior of an automaton is possible, even when a portion of its past history is unknown.
Abstract: : The most important characteristic of a finite automaton is that it has a memory. By this we mean that the behavior of an automaton is depend ent upon its past history. In this report sever al special cases are studied in which the unique determination of the behavior of an automaton is possible, even when a portion of its past history is unknown.
16 citations
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07 Jul 2003TL;DR: Deterministic and nondeterministic flip-pushdown automata accepting by final state or empty pushdown are investigated and it is shown that nondeterminism is better than determinism.
Abstract: Flip-pushdown automata are pushdown automata with the additional ability to flip or reverse its pushdown We investigate deterministic and nondeterministic flip-pushdown automata accepting by final state or empty pushdown In particular, for nondeterministic flip-pushdown automata both acceptance criterion are equally powerful, while for determinism, acceptance by empty pushdown is strictly weaker This nicely fits into the well-known results on ordinary pushdown automata Moreover, we consider hierarchies of flip-pushdown automata wrt the number of pushdown reversals There we show that nondeterminism is better than determinism Moreover, since there are languages which can be recognized by a deterministic flip-pushdown automaton with k + 1 pushdown reversals but which cannot be recognized by a k-flip-pushdown (deterministic or nondeterministic) as shown in [9] we are able to complete our investigations with incomparability results on different levels of the hierarchies under consideration
16 citations
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TL;DR: This paper demonstrates that the same worst-case 2 ?
16 citations