2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/133883In this paper we prove a separability criterion for mixed states in $\mathbb C^p\otimes\mathbb C^q$. We also show that the density matrix of a graph with only one entangled edge is entangled.Part of M.Sc. Thesis of the first authorInformation TheoryDiscrete Mathematicstext