A morphic representation of EOL languages and other ETOL languages

AbstractThe following morphic characterization of EOL languages is established. The family of EOL languages equals the family of all languages of the form h(L∩R) where h is a morphism, R is a regular language and L is the maximal solution of an equation ⨍(X) = g(X), where ⨍ is a morphism, g is a coding and X is a language variable. It is shown that if g is allowed to be a weak coding, then a larger family of languages is obtained, which however is strictly contained in the family of ETOL languages