2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/59581The property that a one to one function from the natural numbers to itself preserves the density of sub-sets is shown to be equivalent to a condition on the covering of intervals in the range of the function by images of intervals in the domain of the function.11 pagesGeneral MathematicsProbabilitytext