Decidability of Equivalence for a Class of Non-Deterministic Tree Transducers

In this paper, we consider non-deterministic tree transducers in the letter to letter case, that is to say tree transducers for which trees which appear in the rules are reduced to one letter in the right-hand side as in the left one. We establish the decidability of equivalence for linear and non-deleting top-down transducers. These results are valid in the bottom-up case. R esum e Nous consid erons des transducteurs non d eterministes d'arbres dans le cas lettre a lettre. Nous etablissons la d ecidabilit e de l' equivalence pour les transducteurs descendants lin eaires et complets. Ces r esultats s' etendent au cas des transducteurs ascendants. 2