6-orthoplex

Regular 6 dimensional polytope From Wikipedia, the free encyclopedia

In geometry, a 6-orthoplex, or 6-cross polytope, is a regular 6-polytope with 12 vertices, 60 edges, 160 triangle faces, 240 tetrahedron cells, 192 5-cell 4-faces, and 64 5-faces.

More information 6-orthoplex Hexacross ...
6-orthoplex
Hexacross

Orthogonal projection
inside Petrie polygon
TypeRegular 6-polytope
Familyorthoplex
Schläfli symbols{3,3,3,3,4}
{3,3,3,31,1}
Coxeter-Dynkin diagrams
=
5-faces64 {34}
4-faces192 {33}
Cells240 {3,3}
Faces160 {3}
Edges60
Vertices12
Vertex figure5-orthoplex
Petrie polygondodecagon
Coxeter groupsB6, [4,34]
D6, [33,1,1]
Dual6-cube
Propertiesconvex, Hanner polytope
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It has two constructed forms, the first being regular with Schläfli symbol {34,4}, and the second with alternately labeled (checkerboarded) facets, with Schläfli symbol {3,3,3,31,1} or Coxeter symbol 311.

It is a part of an infinite family of polytopes, called cross-polytopes or orthoplexes. The dual polytope is the 6-hypercube, or hexeract.

Alternate names

As a configuration

This configuration matrix represents the 6-orthoplex. The rows and columns correspond to vertices, edges, faces, cells, 4-faces and 5-faces. The diagonal numbers say how many of each element occur in the whole 6-orthoplex. The nondiagonal numbers say how many of the column's element occur in or at the row's element.[2][3]

Construction

There are three Coxeter groups associated with the 6-orthoplex, one regular, dual of the hexeract with the C6 or [4,3,3,3,3] Coxeter group, and a half symmetry with two copies of 5-simplex facets, alternating, with the D6 or [33,1,1] Coxeter group. A lowest symmetry construction is based on a dual of a 6-orthotope, called a 6-fusil.

More information Name, Coxeter ...
Name Coxeter Schläfli Symmetry Order
Regular 6-orthoplex {3,3,3,3,4} [4,3,3,3,3]46080
Quasiregular 6-orthoplex {3,3,3,31,1} [3,3,3,31,1]23040
6-fusil {3,3,3,4}+{}[4,3,3,3,3]7680
{3,3,4}+{4}[4,3,3,2,4]3072
2{3,4}[4,3,2,4,3]2304
{3,3,4}+2{}[4,3,3,2,2]1536
{3,4}+{4}+{}[4,3,2,4,2]768
3{4}[4,2,4,2,4]512
{3,4}+3{}[4,3,2,2,2]384
2{4}+2{}[4,2,4,2,2]256
{4}+4{}[4,2,2,2,2]128
6{} [2,2,2,2,2]64
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Cartesian coordinates

Cartesian coordinates for the vertices of a 6-orthoplex, centered at the origin are

(±1,0,0,0,0,0), (0,±1,0,0,0,0), (0,0,±1,0,0,0), (0,0,0,±1,0,0), (0,0,0,0,±1,0), (0,0,0,0,0,±1)

Every vertex pair is connected by an edge, except opposites.

Images

More information Coxeter plane, B ...
Orthographic projections
Coxeter plane B6 B5 B4
Graph
Dihedral symmetry [12] [10] [8]
Coxeter plane B3 B2
Graph
Dihedral symmetry [6] [4]
Coxeter plane A5 A3
Graph
Dihedral symmetry [6] [4]
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The 6-orthoplex can be projected down to 3-dimensions into the vertices of a regular icosahedron.[4]

More information 2D, 3D ...
2D 3D

Icosahedron
{3,5} =
H3 Coxeter plane

6-orthoplex
{3,3,3,31,1} =
D6 Coxeter plane

Icosahedron

6-orthoplex
This construction can be geometrically seen as the 12 vertices of the 6-orthoplex projected to 3 dimensions as the vertices of a regular icosahedron. This represents a geometric folding of the D6 to H3 Coxeter groups: : to . On the left, seen by these 2D Coxeter plane orthogonal projections, the two overlapping central vertices define the third axis in this mapping. Every pair of vertices of the 6-orthoplex are connected, except opposite ones: 30 edges are shared with the icosahedron, while 30 more edges from the 6-orthoplex project to the interior of the icosahedron.
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It is in a dimensional series of uniform polytopes and honeycombs, expressed by Coxeter as 3k1 series. (A degenerate 4-dimensional case exists as 3-sphere tiling, a tetrahedral hosohedron.)

More information , ...
3k1 dimensional figures
Space Finite Euclidean Hyperbolic
n 4 5 6 7 8 9
Coxeter
group
A3A1 A5 D6 E7 =E7+ =E7++
Coxeter
diagram
Symmetry [3−1,3,1] [30,3,1] [[31,3,1]]
= [4,3,3,3,3]
[32,3,1] [33,3,1] [34,3,1]
Order 48 720 46,080 2,903,040
Graph - -
Name 31,-1 310 311 321 331 341
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This polytope is one of 63 uniform 6-polytopes generated from the B6 Coxeter plane, including also the regular 6-cube.

Notes

References

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