Relating the type of ambiguity of finite automata to the succinctness of their representation
SIAM Journal on Computing
Making Nondeterminism Unambiguous
SIAM Journal on Computing
Two-way automata simulations and unary languages
Journal of Automata, Languages and Combinatorics
Introduction To Automata Theory, Languages, And Computation
Introduction To Automata Theory, Languages, And Computation
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
Deterministic moles cannot solve liveness
Journal of Automata, Languages and Combinatorics
Unary finite automata vs. arithmetic progressions
Information Processing Letters
Size Complexity of Two-Way Finite Automata
DLT '09 Proceedings of the 13th International Conference on Developments in Language Theory
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
Relationships between nondeterministic and deterministic tape complexities
Journal of Computer and System Sciences
Space-bounded reducibility among combinatorial problems
Journal of Computer and System Sciences
ICALP'03 Proceedings of the 30th international conference on Automata, languages and programming
Two-way automata versus logarithmic space
CSR'11 Proceedings of the 6th international conference on Computer science: theory and applications
Nondeterminism is essential in small 2FAs with few reversals
ICALP'11 Proceedings of the 38th international conference on Automata, languages and programming - Volume Part II
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We show that each n-state unary 2nfa (a two-way nondeterministic finite automaton) can be simulated by an equivalent 2ufa (an unambiguous 2nfa) with a polynomial number of states. Moreover, if L = NL (the classical logarithmic space classes), then each unary 2nfa can be converted into an equivalent 2DFA (a deterministic two-way automaton), still keeping polynomial the number of states. This shows a connection between the standard logarithmic space complexity and the state complexity of two-way unary automata: it indicates that L could be separated from NL by proving a superpolynomial gap, in the number of states, for the conversion from unary 2NFAS to 2DFAS.