Concatention of inputs in a two-way automation
Theoretical Computer Science
A note on the reduction of two-way automata to one-way atuomata
Information Processing Letters
Handbook of theoretical computer science (vol. B)
Two-way automata simulations and unary languages
Journal of Automata, Languages and Combinatorics
Optimal Simulations between Unary Automata
SIAM Journal on Computing
Proceedings of the 7th Colloquium on Automata, Languages and Programming
Converting two-way nondeterministic unary automata into simpler automata
Theoretical Computer Science - Mathematical foundations of computer science
Nondeterminism and the size of two way finite automata
STOC '78 Proceedings of the tenth annual ACM symposium on Theory of computing
Lower bounds on the size of sweeping automata
STOC '79 Proceedings of the eleventh annual ACM symposium on Theory of computing
Errata to: "finite automata and unary languages"
Theoretical Computer Science
On the State Complexity of Operations on Two-Way Finite Automata
DLT '08 Proceedings of the 12th international conference on Developments in Language Theory
Descriptional and Computational Complexity of Finite Automata
LATA '09 Proceedings of the 3rd International Conference on Language and Automata Theory and Applications
Finite automata and their decision problems
IBM Journal of Research and Development
The reduction of two-way automata to one-way automata
IBM Journal of Research and Development
Removing bidirectionality from nondeterministic finite automata
MFCS'05 Proceedings of the 30th international conference on Mathematical Foundations of Computer Science
State complexity of operations on two-way deterministic finite automata over a unary alphabet
DCFS'11 Proceedings of the 13th international conference on Descriptional complexity of formal systems
Unambiguous finite automata over a unary alphabet
Information and Computation
State complexity of operations on two-way finite automata over a unary alphabet
Theoretical Computer Science
State Complexity of Union and Intersection for Two-way Nondeterministic Finite Automata
Fundamenta Informaticae - Theory that Counts: To Oscar Ibarra on His 70th Birthday
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A framework for the study of periodic behaviour of two-way deterministic finite automata (2DFA) is developed. Computations of 2DFAs are represented by a two-way analogue of transformation semigroups, every element of which describes the behaviour of a 2DFA on a certain string x. A subsemigroup generated by this element represents the behaviour on strings in x+. The main contribution of this paper is a description of all such monogenic subsemigroups up to isomorphism. This characterization is then used to show that transforming an n-state 2DFA over a one-letter alphabet to an equivalent sweeping 2DFA requires exactly n+1 states, and transforming it to a one-way automaton requires exactly max0≤l≤n G(n - l) + l + 1 states, where G(k) is the maximum order of a permutation of k elements.