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ACM Transactions on Information Systems (TOIS)
We show that the nonemptiness problem for two-way automata with only one endmarker over unary alphabets is complete for nondeterministic logarithmic space. This should be contrasted with the corresponding problem for two-way automata with two endmarkers, which is known to be NP-complete. © 1990.
Chidanand Apté, Fred Damerau, et al.
ACM Transactions on Information Systems (TOIS)
Fan Zhang, Junwei Cao, et al.
IEEE TETC
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