On the concept of fractality for groups of automorphisms of a regular rooted tree

L'objectiu d'aquest article és discutir i aclarir la noció de fractalitat per a subgrupsdel grup d'automorfismes d'un arbre arrelat i regular. Per això, definim tres tipusde fractalitat i demostrem, donant contraexemples, que no són equivalents. Tambépresentem alguns resultats que ajuden a determinar el tipus de fractalitat d'ungrup donat.The aim of this article is to discuss and clarify the notion of fractality for subgroups of the group of automorphisms of a regular rooted tree. For this purpose, we dene three types of fractality. We show that they are not equivalent, by giving explicit counter-examples. Furthermore, we present some tools that are helpful in order to determine the fractality of a given group. &nbsp