A note on the equivalence problem of rational formal power series. (English) Zbl 0609.68055

It is shown that the equivalence problem for K-\(\Sigma\)-automata is undecidable for a commutative semiring K. This contrasts with the Equality Theorem of Eilenberg which implies that the problem is decidable if K is a field.


68Q45 Formal languages and automata
16Y60 Semirings
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