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In mathematics, quaternionic projective space is an extension of the ideas of real projective space and complex projective space, to the case where coordinates lie in the ring of quaternions H. Quaternionic projective space of dimension ''n'' is usually denoted by : and is a closed manifold of (real) dimension 4''n''. It is a homogeneous space for a Lie group action, in more than one way. ==In coordinates== Its direct construction is as a special case of the projective space over a division algebra. The homogeneous coordinates of a point can be written : where the are quaternions, not all zero. Two sets of coordinates represent the same point if they are 'proportional' by a left multiplication by a non-zero quaternion ''c''; that is, we identify all the :. In the language of group actions, is the orbit space of by the action of , the multiplicative group of non-zero quaternions. By first projecting onto the unit sphere inside one may also regard as the orbit space of by the action of , the group of unit quaternions.〔Gregory L. Naber, ''Topology, geometry, and gauge fields: foundations'' (1997), p. 50.〕 The sphere then becomes a principal Sp(1)-bundle over : : There is also a construction of by means of two-dimensional complex subspaces of , meaning that lies inside a complex Grassmannian. 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「Quaternionic projective space」の詳細全文を読む スポンサード リンク
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