Kosaburo Hashiguchi

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Let W= {R,, . . . . R,} be a finite class of regular languages over a finite alphabet Z. Let A = {b,, . . . . 6,) be an alphabet, and 6 be the substitution from A* into Z* such that S(b,) = R, for all i (1 < id m). Let R be a regular language over Z which can be defined from %? by a finite number of applications of the operators union, concatenation, and(More)
A homomorphism f from the set of words over a finite alphabet Z' 1 to the set of words over another finite alphabet X 2 is said to preserve star height if for all regula r events R _C Z'~*, the star height of R is equal to that off(R). An algorithm is presented for deciding whether an arbitrary homomorphism preserves star height or not: in our result, the(More)