2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/169432The aim of this note is to describe the Poisson boundary of the group of invertible triangular matrices with coefficients in a number field. It generalizes to any dimension and to any number field a result of Brofferio concerning the Poisson boundary of random rational affinities.to appear in Annales Institut FourierProbability22D40; 28D05; 28D20; 60B15; 60J10; 60J50.text