Unambiguous erasing morphisms in free monoids
This paper discusses the fundamental combinatorial question of whether or not, for a given string , there exists a morphism such that is unambiguous with respect to , there exists no other morphism satisfying () = (). While Freydenberger [ (2006) 601–628] characterise those strings for which there exists an unambiguous morphism , little is known about the unambiguity of morphisms, morphisms that map symbols onto the empty string. The present paper demonstrates that, in contrast...