2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/126486Define an outer measure on R^n by taking the infimum, over all covers of the set by tubes, of the sum of the cross-sectional areas of the tubes. We show that the only measurable sets for this outer measure are its null sets and their complements.4 pagesClassical Analysis and ODEs28A12text