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In mathematics, a Lie groupoid is a groupoid where the set of objects and the set of morphisms are both manifolds, the source and target operations : are submersions, and all the category operations (source and target, composition, and identity-assigning map) are smooth. A Lie groupoid can thus be thought of as a "many-object generalization" of a Lie group, just as a groupoid is a many-object generalization of a group. Just as every Lie group has a Lie algebra, every Lie groupoid has a Lie algebroid. ==Examples== *Any Lie group gives a Lie groupoid with one object, and conversely. So, the theory of Lie groupoids includes the theory of Lie groups. *Given any manifold , there is a Lie groupoid called the pair groupoid, with as the manifold of objects, and precisely one morphism from any object to any other. In this Lie groupoid the manifold of morphisms is thus . *Given a Lie group acting on a manifold , there is a Lie groupoid called the translation groupoid with one morphism for each triple with . *Any foliation gives a Lie groupoid. *Any principal bundle with structure group ''G'' gives a groupoid, namely over ''M'', where ''G'' acts on the pairs componentwise. Composition is defined via compatible representatives as in the pair groupoid. 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「Lie groupoid」の詳細全文を読む スポンサード リンク
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