2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/92325We study the entanglement feature of the ground state of a system composed of spin 1 and 1/2 parts. The concurrence vector is shown to be consistent with the measurement of von Neumann entropy for such system. In the light of the ground state degeneracy, we suggest a average concurrence to measure the entanglement of Hilbert subspace. The entanglement property of both a general superposition as well as the mixture of the degenerate ground states are discussed by means of average concurrence and the negativity respectively.5 pages, 4 figures; one figure is replaced and one subsection is revisedQuantum Physicstext