2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/92506We use open quantum system techniques to construct one-parameter semigroups of positive maps and apply them to study the entanglement properties of a class of 16-dimensional density matrices, representing states of a 4x4 bipartite system.15 pages, to appear on "Open systems & information dynamics", OSID styleQuantum Physicstext