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<p></p> <p><b>New page</b></p><div>{{Expert-subject|date=November 2010}}<br /> {{Unreferenced|date=November 2010}}<br /> Given a [[unital algebra|unital]] [[C*-algebra]] &lt;math&gt; \mathcal{A} &lt;/math&gt;, a [[C*-algebra|*-closed]] [[linear subspace|subspace]] &#039;&#039;S&#039;&#039; containing &#039;&#039;1&#039;&#039; is called an &#039;&#039;&#039;operator system&#039;&#039;&#039;. One can associate to each subspace &lt;math&gt; \mathcal{M} \subseteq \mathcal{A} &lt;/math&gt; of a unital C*-algebra an operator system via &lt;math&gt; S:= \mathcal{M}+\mathcal{M}^* +\mathbb{C} 1 &lt;/math&gt;.<br /> <br /> The appropriate morphisms between operator systems are [[completely positive map]]s.<br /> <br /> By a theorem of Choi and Effros, operator systems can be characterized as *-vector spaces equipped with an Archimedean matrix order.<br /> <br /> <br /> [[Category:Operator theory]]<br /> <br /> [[Category:Operator algebras]]<br /> <br /> <br /> {{mathanalysis-stub}}</div>

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