2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/90707A direct proof of the relation between the one-shot classical capacity and the minimal output entropy for covariant quantum channels is suggested. The structure of covariant channels is described in some detail. A simple proof of a general inequality for entanglement-assisted classical capacity is given.6 pagesQuantum Physicstext