2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/109313We thoroughly analyse the distance between quantum states that has been applied to state-dependent cloning and partly studied in the previous work of the author [Phys. Rev. A 66, 042304 (2002)]. Elementary proofs of its significant properties are given.6 pages, no figuresQuantum Physicstext