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In mathematics, a filtered algebra is a generalization of the notion of a graded algebra. Examples appear in many branches of mathematics, especially in homological algebra and representation theory. A filtered algebra over the field is an algebra over which has an increasing sequence of subspaces of such that : ==Associated graded algebra== In general there is the following construction that produces a graded algebra out of a filtered algebra. If is a filtered algebra then the ''associated graded algebra'' is defined as follows: G_n\,, where, : and : |2= the multiplication is defined by : for all and . (More precisely, the multiplication map is combined from the maps : for all and .) }} The multiplication is well defined and endows with the structure of a graded algebra, with gradation . Also if is unital, such that the unit lies in , then will be unital as well. As algebras and are distinct (with the exception of the trivial case that is graded) but as vector spaces they are isomorphic. 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「filtered algebra」の詳細全文を読む スポンサード リンク
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