2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/64126Let R be a commutative ring and let n,m be two positive integers. Let be the polynomial ring in m x n commuting independent variables R. The symmetric group on n letters acts diagonally on A(n,m). We give generators and relations of the rings of invariants for this action.12 pages, amsppt texRings and AlgebrasCombinatoricsRepresentation Theory20c30;16W22;05E05text