2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/56939We give necessary and sufficient conditions for non-conservativity of a class of minimal quantum dynamical semigroups (qds). We extend some well known criteria for conservativity of minimal qds and show interesting relations of the conservativity problem with the von Neumann theory of the defect indices of a symmetric closed operator.22 pagesMathematical PhysicsProbability81S25 (Primary) 47N50 (Secondary)text