Journal of the ACM (JACM)
An Infinite Hierarchy of Context-Free Languages
Journal of the ACM (JACM)
Deterministic Pushdown Store Machines and Real-Time Computation
Journal of the ACM (JACM)
A Generalization of Ogden's Lemma
Journal of the ACM (JACM)
Algebraic and Automata-Theoretic Properties of Formal Languages
Algebraic and Automata-Theoretic Properties of Formal Languages
Mathematical Theory of L Systems
Mathematical Theory of L Systems
Flip-pushdown automata: k + 1 pushdown reversals are better than k
ICALP'03 Proceedings of the 30th international conference on Automata, languages and programming
Input-Driven queue automata: finite turns, decidability, and closure properties
CIAA'13 Proceedings of the 18th international conference on Implementation and Application of Automata
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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 w.r.t. 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.