顶点图 : 三角柱 5个面: 2(3.3.3 )和3(3.4.3.4 )
截半超立方体 (Rectified tesseract ),在四维 几何学 中,是一个由16个正四面体和8个截半立方体胞 组成的均匀多胞体 。每条棱都连接到一个正四面体和两个截半立方体。每个顶点周围环绕着两个正四面体 和三个截半立方体 。它总共有88个面(64个三角形面和24个正方形面),96条棱和32个顶点。它的顶点图 是正三角柱 。
构造
截角正五胞体的细胞可以通过在正五胞体 的棱的三分点处截断其顶点。截断的五个正四面体 变成新的截角四面体 ,并在原来的顶点处产生了五个新的正四面体 。
结合
截角四面体 的六边形面彼此结合在一起,而它们的三角形面则连接到正四面体 。
投影
施莱格尔投影 (对着一个截半立方体 胞)
展开图
截半立方体 为中心的3维透视投影,最接近的截半立方体呈红色,周围的4个截半立方体呈绿色。远端的胞清晰度降低(虽然可以从棱看出它们)。投影只是在三维空间中旋转,而不是在四维空间中旋转。
坐标
一个棱长为
2
{\displaystyle {\sqrt {2}}}
的截半超立方体的顶点的笛卡儿坐标系 坐标
(
0
,
0
,
0
,
0
)
{\displaystyle \left(0,\ 0,\ 0,\ 0\right)}
(
2
5
,
2
6
,
2
3
,
0
)
{\displaystyle \left({\sqrt {\frac {2}{5}}},\ {\frac {2}{\sqrt {6}}},\ {\frac {2}{\sqrt {3}}},\ 0\right)}
(
2
5
,
2
6
,
−
1
3
,
±
1
)
{\displaystyle \left({\sqrt {\frac {2}{5}}},\ {\frac {2}{\sqrt {6}}},\ {\frac {-1}{\sqrt {3}}},\ \pm 1\right)}
(
2
5
,
−
2
6
,
1
3
,
±
1
)
{\displaystyle \left({\sqrt {\frac {2}{5}}},\ {\frac {-2}{\sqrt {6}}},\ {\frac {1}{\sqrt {3}}},\ \pm 1\right)}
(
2
5
,
−
2
6
,
−
2
3
,
0
)
{\displaystyle \left({\sqrt {\frac {2}{5}}},\ {\frac {-2}{\sqrt {6}}},\ {\frac {-2}{\sqrt {3}}},\ 0\right)}
(
−
3
10
,
1
6
,
1
3
,
±
1
)
{\displaystyle \left({\frac {-3}{\sqrt {10}}},\ {\frac {1}{\sqrt {6}}},\ {\frac {1}{\sqrt {3}}},\ \pm 1\right)}
(
−
3
10
,
1
6
,
−
2
3
,
0
)
{\displaystyle \left({\frac {-3}{\sqrt {10}}},\ {\frac {1}{\sqrt {6}}},\ {\frac {-2}{\sqrt {3}}},\ 0\right)}
(
−
3
10
,
−
3
2
,
0
,
0
)
{\displaystyle \left({\frac {-3}{\sqrt {10}}},\ -{\sqrt {\frac {3}{2}}},\ 0,\ 0\right)}
更简单的,截半正五胞体的顶点是五维空间笛卡儿坐标系 的(0,0,0,1,1)或(0,0,1,1,1)的全排列。
参考文献
H.S.M. Coxeter :
H.S.M. Coxeter, Regular Polytopes , 3rd Edition, Dover New York, 1973
Kaleidoscopes: Selected Writings of H.S.M. Coxeter , editied by F. Arthur Sherk, Peter McMullen, Anthony C. Thompson, Asia Ivic Weiss, Wiley-Interscience Publication, 1995, ISBN 978-0-471-01003-6 [1] (页面存档备份 ,存于互联网档案馆 )
(Paper 22) H.S.M. Coxeter, Regular and Semi Regular Polytopes I , [Math. Zeit. 46 (1940) 380-407, MR 2,10]
(Paper 23) H.S.M. Coxeter, Regular and Semi-Regular Polytopes II , [Math. Zeit. 188 (1985) 559-591]
(Paper 24) H.S.M. Coxeter, Regular and Semi-Regular Polytopes III , [Math. Zeit. 200 (1988) 3-45]
Norman Johnson Uniform Polytopes , Manuscript (1991)
N.W. Johnson: The Theory of Uniform Polytopes and Honeycombs , Ph.D. (1966)
2. Convex uniform polychora based on the tesseract (8-cell) and hexadecachoron (16-cell) - Model 11 , George Olshevsky.
Klitzing, Richard. 4D uniform polytopes (polychora) o4x3o3o - rit . bendwavy.org.
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