2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/69481Order unit property of a positive element in a $C^{*}$-algebra is defined. It is proved that precisely projections satisfy this order theoretic property. This way, unital hereditary $C^{*}$-subalgebras of a $C^{*}$-algebra are characterized.5 pages, no figures, no tablesOperator Algebrastext