A generalization of Parikh's semilinear theorem

AbstractThe operation of nested iterated substitution preserves languages with the semilinear property. As a consequence, the following generalization of Parikh's theorem that each context-free language has the semilinear property is obtained: If \tL is a family of languages with the semilinear property closed under intersection with regular sets and finite substitution, all members of the least superAFL containing \tL have the semilinear property