2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/126515We derive the Josephson relation in a superfluid between the condensate density, the superfluid mass density, and the infrared structure of the single particle Green's function by means of diagrammatic perturbation theory. The derivation is valid for finite systems and two dimensions.4 pages, no figuresStatistical Mechanicstext