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A graded category is a mathematical concept. If is a category, then a -graded category is a category together with a functor . Monoids and groups can be thought of as categories with a single element. A monoid-graded or group-graded category is therefore one in which to each morphism is attached an element of a given monoid (resp. group), its grade. This must be compatible with composition, in the sense that compositions have the product grade. ==Definition== There are various different definitions of a graded category, up to the most abstract one given above. A more concrete definition of a semigroup-graded Abelian category is as follows: Let be an Abelian category and a semigroup. Let be a set of functors from to itself. If * is the identity functor on , * for all and * is a full and faithful functor for every we say that is a -graded category. 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「Graded category」の詳細全文を読む スポンサード リンク
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