Conjugacy and episturmian morphisms
Résumé
Episturmian morphisms generalize Sturmian morphisms. Here, we study some intrinsic properties of these morphisms: invertibility, presentation, cancellativity, unitarity, characterization by conjugacy. Most of them are generalizations of known properties of Sturmian morphisms. But we present also some results on episturmian morphisms that have not already been stated in the particular case of Sturmian morphisms: characterization of the episturmian morphisms that preserve palindromes, new algorithms to compute conjugates. We also study the conjugation of morphisms in the general case and show that the monoid of invertible morphisms on an alphabet containing at least three letters is not finitely generated.