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:''For the same-name concept in differential geometry, see immersion (mathematics).'' In algebraic geometry, a closed immersion of schemes is a morphism of schemes that identifies ''Z'' as a closed subset of ''X'' such that regular functions on ''Z'' can be extended locally to ''X''.〔Mumford, ''The Red Book of Varieties and Schemes'', Section II.5〕 The latter condition can be formalized by saying that is surjective. An example is the inclusion map induced by the canonical map . ==Other characterizations== The following are equivalent: # is a closed immersion. #For every open affine , there exists an ideal such that as schemes over ''U''. #There exists an open affine covering and for each ''j'' there exists an ideal such that as schemes over . #There is a quasi-coherent sheaf of ideals on ''X'' such that and ''f'' is an isomorphism of ''Z'' onto the global Spec of over ''X''. 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「Closed immersion」の詳細全文を読む スポンサード リンク
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