2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/69904In these notes we investigate the rings of real polynomials in four variables, which are invariant under the action of the reflectiongroups [3,4,3] and [3,3,5]. It is well known that they are rationally generated in degree 2,6,8,12 and 2,12,20,30. We give a different proof of this fact by giving explicit equations for the generating polynomials.10 pagesAlgebraic Geometry14L24; 14L30text