On Standard Sturmian Morphisms

摘要

We give a characterization of morphisms which preserve finite and infinite standard Sturmian words. The class of such morphisms coincides with the monoid {D,E} sup * of the endomorphisms of A sup *, where A={a,b}, generated by the two elementary morphisms, E which interchanges the letter a with b and D which is the Fibonacci morphism defined as: D(a) =ab, D(b)=a. Some new properties of these morphisms are shown. In particular, we derive a new characterization of the set PER of all works w having two eproids p and q which are ocmprimes and such that w=p+q-2.