2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/160136We give a combinatorial rule for computing intersection numbers on a flag manifold which come from products of Schubert classes pulled back from Grassmannian projections. This rule generalizes the known rule for Grassmannians.10 pages, colour diagrams. Corrected an exampleCombinatorics05E10, 14N15text