2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/168631These notes cover background material on trees which are used in the paper `On uniqueness of the signature of a path of variation and the reduced path group'.Background material for the paper `On uniqueness of the signature of a path of variation and the reduced path group'. Formerly an appendix to earlier versions of the paperClassical Analysis and ODEsProbability54F50; 05C05text