6-simplex
Type uniform polypeton
Schläfli symbol {35}
Coxeter diagrams           Elements

f5 = 7, f4 = 21, C = 35, F = 35, E = 21, V = 7
(χ=0)

Coxeter group A6, , order 5040
Bowers name
and (acronym)
Heptapeton
(hop)
Vertex figure 5-simplex
Circumradius ${\sqrt {\tfrac {3}{7)))$ 0.654654
Properties convex, isogonal self-dual

In geometry, a 6-simplex is a self-dual regular 6-polytope. It has 7 vertices, 21 edges, 35 triangle faces, 35 tetrahedral cells, 21 5-cell 4-faces, and 7 5-simplex 5-faces. Its dihedral angle is cos−1(1/6), or approximately 80.41°.

## Alternate names

It can also be called a heptapeton, or hepta-6-tope, as a 7-facetted polytope in 6-dimensions. The name heptapeton is derived from hepta for seven facets in Greek and -peta for having five-dimensional facets, and -on. Jonathan Bowers gives a heptapeton the acronym hop.

## As a configuration

This configuration matrix represents the 6-simplex. 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-simplex. The nondiagonal numbers say how many of the column's element occur in or at the row's element. This self-dual simplex's matrix is identical to its 180 degree rotation.

${\begin{bmatrix}{\begin{matrix}7&6&15&20&15&6\\2&21&5&10&10&5\\3&3&35&4&6&4\\4&6&4&35&3&3\\5&10&10&5&21&2\\6&15&20&15&6&7\end{matrix))\end{bmatrix))$ ## Coordinates

The Cartesian coordinates for an origin-centered regular heptapeton having edge length 2 are:

$\left({\sqrt {1/21)),\ {\sqrt {1/15)),\ {\sqrt {1/10)),\ {\sqrt {1/6)),\ {\sqrt {1/3)),\ \pm 1\right)$ $\left({\sqrt {1/21)),\ {\sqrt {1/15)),\ {\sqrt {1/10)),\ {\sqrt {1/6)),\ -2{\sqrt {1/3)),\ 0\right)$ $\left({\sqrt {1/21)),\ {\sqrt {1/15)),\ {\sqrt {1/10)),\ -{\sqrt {3/2)),\ 0,\ 0\right)$ $\left({\sqrt {1/21)),\ {\sqrt {1/15)),\ -2{\sqrt {2/5)),\ 0,\ 0,\ 0\right)$ $\left({\sqrt {1/21)),\ -{\sqrt {5/3)),\ 0,\ 0,\ 0,\ 0\right)$ $\left(-{\sqrt {12/7)),\ 0,\ 0,\ 0,\ 0,\ 0\right)$ The vertices of the 6-simplex can be more simply positioned in 7-space as permutations of:

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

This construction is based on facets of the 7-orthoplex.

## Related uniform 6-polytopes

The regular 6-simplex is one of 35 uniform 6-polytopes based on the [3,3,3,3,3] Coxeter group, all shown here in A6 Coxeter plane orthographic projections.

1. ^ Klitzing, Richard. "heptapeton". bendwavy.org.
2. ^ Klitzing, Richard. "6D uniform polytopes (polypeta) x3o3o3o3o3o — hop".
3. ^ Coxeter 1973, §1.8 Configurations
4. ^ Coxeter, H.S.M. (1991). Regular Complex Polytopes (2nd ed.). Cambridge University Press. p. 117. ISBN 9780521394901.
Family An Bn I2(p) / Dn E6 / E7 / E8 / F4 / G2 Hn
Regular polygon Triangle Square p-gon Hexagon Pentagon
Uniform polyhedron Tetrahedron OctahedronCube Demicube DodecahedronIcosahedron
Uniform polychoron Pentachoron 16-cellTesseract Demitesseract 24-cell 120-cell600-cell
Uniform 5-polytope 5-simplex 5-orthoplex5-cube 5-demicube
Uniform 6-polytope 6-simplex 6-orthoplex6-cube 6-demicube 122221
Uniform 7-polytope 7-simplex 7-orthoplex7-cube 7-demicube 132231321
Uniform 8-polytope 8-simplex 8-orthoplex8-cube 8-demicube 142241421
Uniform 9-polytope 9-simplex 9-orthoplex9-cube 9-demicube
Uniform 10-polytope 10-simplex 10-orthoplex10-cube 10-demicube
Uniform n-polytope n-simplex n-orthoplexn-cube n-demicube 1k22k1k21 n-pentagonal polytope
Topics: Polytope familiesRegular polytopeList of regular polytopes and compounds