2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/71029Necessary and sufficient condition is given for a set $A\subset R^1$ to be a subset of the critical values set for a $C^k$ function $f:R^m \to R^1$.8 pagesClassical Analysis and ODEsGeometric TopologyPrimary: 58K05; Secondary: 58C25text