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In mathematics the Lawrence–Krammer representation is a representation of the braid groups. It fits into a family of representations called the Lawrence representations. The 1st Lawrence representation is the Burau representation and the 2nd is the Lawrence–Krammer representation. The Lawrence–Krammer representation is named after Ruth Lawrence and Daan Krammer. == Definition == Consider the braid group to be the mapping class group of a disc with ''n'' marked points . The Lawrence–Krammer representation is defined as the action of on the homology of a certain covering space of the configuration space . Specifically, , and the subspace of invariant under the action of is primitive, free and of rank 2. Generators for this invariant subspace are denoted by . The covering space of corresponding to the kernel of the projection map : is called the Lawrence–Krammer cover and is denoted . Diffeomorphisms of act on , thus also on , moreover they lift uniquely to diffeomorphisms of which restrict to identity on the co-dimension two boundary stratum (where both points are on the boundary circle). The action of on : thought of as a :-module, is the Lawrence–Krammer representation. is known to be a free -module, of rank . 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「Lawrence–Krammer representation」の詳細全文を読む スポンサード リンク
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