2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/120288Let $f:I\to X$ be a d.c. mapping, where $I\subset \R$ is an open interval and $X$ a Banach space. Let $C_f$ be the set of critical points of $f$. We prove that $f(C_f)$ has zero 1/2-dimensional Hausdorff measure.4 pagesFunctional Analysis26A51text