Highly Influenced

@article{Ibarra1977TheUO, title={The unsolvability of the equivalence problem for e-free NGSM's with unary input (output) alphabet and applications}, author={Oscar H. Ibarra}, journal={18th Annual Symposium on Foundations of Computer Science (sfcs 1977)}, year={1977}, pages={74-81} }

- Published 1977 in 18th Annual Symposium on Foundations of Computer…

It is shown that the equivalence problem is unsolvable for ε-free nondeterministic generalized sequential machines whose input/output are restricted to unary/binary (binary/unary) alphabets. This strengthens a known result of Griffiths. Applications to some decision problems concerning right-linear grammars and directed graphs are also given.

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