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In geometry, a regular skew apeirohedron is an infinite regular skew polyhedron, with either skew regular faces or skew regular vertex figures. ==History== According to Coxeter, in 1926 John Flinders Petrie generalized the concept of regular skew polygons (nonplanar polygons) to finite regular skew polyhedra in 4-dimensions, and infinite regular skew apeirohedra in 3-dimensions (described here). Coxeter identified 3 forms, with planar faces and skew vertex figures, two are compliments of each other. They are all named with a modified Schläfli symbol , where there are ''l''-gonal faces, ''m'' faces around each vertex, with ''holes'' identified as ''n''-gonal missing faces. Coxeter offered a modified Schläfli symbol for these figures, with implying the vertex figure, ''m'' l-gons around a vertex, and ''n''-gonal holes. Their vertex figures are skew polygons, zig-zagging between two planes. The regular skew polyhedra, represented by , follow this equation: * 2 sin(/''l'') · sin(/''m'') = cos(/''n'') 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「regular skew apeirohedron」の詳細全文を読む スポンサード リンク
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