Journal of the ACM (JACM)
Journal of the ACM (JACM)
Characterizations of Pushdown Machines in Terms of Time-Bounded Computers
Journal of the ACM (JACM)
Journal of the ACM (JACM)
Algebraic and Automata-Theoretic Properties of Formal Languages
Algebraic and Automata-Theoretic Properties of Formal Languages
Simple Program Schemes and Formal Languages
Simple Program Schemes and Formal Languages
Introduction To Automata Theory, Languages, And Computation
Introduction To Automata Theory, Languages, And Computation
The Design and Analysis of Computer Algorithms
The Design and Analysis of Computer Algorithms
An Automata-Theoretic Characterization of the OI-Hierarchy
Proceedings of the 9th Colloquium on Automata, Languages and Programming
On Infinite Terms Having a Decidable Monadic Theory
MFCS '02 Proceedings of the 27th International Symposium on Mathematical Foundations of Computer Science
Higher-Order Pushdown Trees Are Easy
FoSSaCS '02 Proceedings of the 5th International Conference on Foundations of Software Science and Computation Structures
Reachability on prefix-recognizable graphs
Information Processing Letters
On Global Model Checking Trees Generated by Higher-Order Recursion Schemes
FOSSACS '09 Proceedings of the 12th International Conference on Foundations of Software Science and Computational Structures: Held as Part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2009
Games on Higher Order Multi-stack Pushdown Systems
RP '09 Proceedings of the 3rd International Workshop on Reachability Problems
Higher order pushdown automata, the Caucal hierarchy of graphs and parity games
ICALP'03 Proceedings of the 30th international conference on Automata, languages and programming
Symbolic backwards-reachability analysis for higher-order pushdown systems
FOSSACS'07 Proceedings of the 10th international conference on Foundations of software science and computational structures
Unsafe grammars and panic automata
ICALP'05 Proceedings of the 32nd international conference on Automata, Languages and Programming
Regular sets over extended tree structures
Theoretical Computer Science
Regular sets of higher-order pushdown stacks
MFCS'05 Proceedings of the 30th international conference on Mathematical Foundations of Computer Science
Symbolic reachability analysis of higher-order context-free processes
FSTTCS'04 Proceedings of the 24th international conference on Foundations of Software Technology and Theoretical Computer Science
Simple models for recursive schemes
MFCS'12 Proceedings of the 37th international conference on Mathematical Foundations of Computer Science
COMPLEXITY AND STRUCTURE IN FORMAL LANGUAGE THEORY
Fundamenta Informaticae
Sequences of level 1, 2, 3,..., k,...
CSR'07 Proceedings of the Second international conference on Computer Science: theory and applications
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An iterated pushdown is a pushdown of pushdowns of ... of pushdowns. An iterated exponential function is 2 to the 2 to the ... to the 2 to some polynomial. The main result is that nondeterministic 2-way and multi-head iterated pushdown automata characterize deterministic iterated exponential time complexity classes. This is proved by investigating both nondeterministic and alternating auxiliary iterated pushdown automata, for which similar characterization results are given. In particular it is shown that alternation corresponds to one more iteration of pushdowns. These results are applied to the 1-way iterated pushdown automata: (1) they form a proper hierarchy with respect to the number of iterations, (2) their emptiness problem is complete in deterministic iterated exponential time.