{{Mi| {{More citations needed|date=September 2014}} {{Original research|date=May 2024}} }}
Given a unital C*-algebra <math> \mathcal{A} </math>, a *-closed subspace ''S'' containing ''1'' is called an '''operator system'''. One can associate to each subspace <math> \mathcal{M} \subseteq \mathcal{A} </math> of a unital C*-algebra an operator system via <math> S:= \mathcal{M}+\mathcal{M}^* +\mathbb{C} 1 </math>.
The appropriate morphisms between operator systems are completely positive maps.
By a theorem of Choi and Effros, operator systems can be characterized as *-vector spaces equipped with an Archimedean matrix order.<ref>Choi M.D., Effros, E.G. Injectivity and operator spaces. Journal of Functional Analysis 1977</ref>
==See also==
==References== {{Reflist}}
Category:Operator theory Category:Operator algebras
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