2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/143420We state some elementary problems concerning the relation between difference calculus and differential calculus, and we try to convince the reader that, in spite of the simplicity of the statements, a solution of these problems would be a significant contribution to the understanding of the foundations of differential and integral calculus.General Mathematics14A25, 39A12, 46S10, 58C20text