2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/56681The imperfect Boson gas supplemented with a gentle repulsive interaction is completely solved. In particular it is proved that it has non-extensive Bose-Einstein condensation, i.e., there is condensation without macroscopic occupation of the ground state (k=0) level.Mathematical Physicstext