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In mathematics, Stinespring's dilation theorem, also called Stinespring's factorization theorem, named after W. Forrest Stinespring, is a result from operator theory that represents any completely positive map on a C *-algebra as a composition of two completely positive maps each of which has a special form: #A *-representation of ''A'' on some auxiliary Hilbert space ''K'' followed by #An operator map of the form ''T'' → ''VTV'' *. Moreover, Stinespring's theorem is a structure theorem from a C *-algebra into the algebra of bounded operators on a Hilbert space. Completely positive maps are shown to be simple modifications of *-representations, or sometimes called *-homomorphisms. == Formulation == In the case of a unital C *-algebra, the result is as follows: :Theorem. Let ''A'' be a unital C *-algebra, ''H'' be a Hilbert space, and ''B(H)'' be the bounded operators on ''H''. For every completely positive :: :there exists a Hilbert space ''K'' and a unital *-homomorphism :: :such that :: :where is a bounded operator. Furthermore, we have :: Informally, one can say that every completely positive map can be "lifted" up to a map of the form . The converse of the theorem is true trivially. So Stinespring's result classifies completely positive maps. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Stinespring factorization theorem」の詳細全文を読む スポンサード リンク
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