# Rectified 6-orthoplexes

In six-dimensional geometry, a rectified 6-orthoplex is a convex uniform 6-polytope, being a rectification of the regular 6-orthoplex.

 Orthogonal projections in B6 Coxeter plane 6-orthoplex Rectified 6-orthoplex Birectified 6-orthoplex Birectified 6-cube Rectified 6-cube 6-cube

There are unique 6 degrees of rectifications, the zeroth being the 6-orthoplex, and the 6th and last being the 6-cube. Vertices of the rectified 6-orthoplex are located at the edge-centers of the 6-orthoplex. Vertices of the birectified 6-orthoplex are located in the triangular face centers of the 6-orthoplex.

## Rectified 6-orthoplex

Rectified hexacross
Typeuniform 6-polytope
Schläfli symbolst1{34,4} or r{34,4}
${\displaystyle \left\{{\begin{array}{l}3,3,3,4\\3\end{array}}\right\}}$
r{3,3,3,31,1}
Coxeter-Dynkin diagrams =
=
5-faces76 total:
64 rectified 5-simplex
12 5-orthoplex
4-faces576 total:
192 rectified 5-cell
384 5-cell
Cells1200 total:
240 octahedron
960 tetrahedron
Faces1120 total:
160 and 960 triangles
Edges480
Vertices60
Vertex figure16-cell prism
Petrie polygonDodecagon
Coxeter groupsB6, [3,3,3,3,4]
D6, [33,1,1]
Propertiesconvex

The rectified 6-orthoplex is the vertex figure for the demihexeractic honeycomb.

or

### Alternate names

• rectified hexacross
• rectified hexacontitetrapeton (acronym: rag) (Jonathan Bowers)

### Construction

There are two Coxeter groups associated with the rectified hexacross, one with the C6 or [4,3,3,3,3] Coxeter group, and a lower symmetry with two copies of pentacross facets, alternating, with the D6 or [33,1,1] Coxeter group.

### Cartesian coordinates

Cartesian coordinates for the vertices of a rectified hexacross, centered at the origin, edge length ${\displaystyle {\sqrt {2}}\ }$ are all permutations of:

(±1,±1,0,0,0,0)

### Images

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]

### Root vectors

The 60 vertices represent the root vectors of the simple Lie group D6. The vertices can be seen in 3 hyperplanes, with the 15 vertices rectified 5-simplices cells on opposite sides, and 30 vertices of an expanded 5-simplex passing through the center. When combined with the 12 vertices of the 6-orthoplex, these vertices represent the 72 root vectors of the B6 and C6 simple Lie groups.

The 60 roots of D6 can be geometrically folded into H3 (Icosahedral symmetry), as to , creating 2 copies of 30-vertex icosidodecahedra, with the Golden ratio between their radii:[1]

Rectified 6-orthoplex 2 icosidodecahedra
3D (H3 projection) A4/B5/D6 Coxeter plane H2 Coxeter plane

## Birectified 6-orthoplex

Birectified 6-orthoplex
Typeuniform 6-polytope
Schläfli symbolst2{34,4} or 2r{34,4}
${\displaystyle \left\{{\begin{array}{l}3,3,4\\3,3\end{array}}\right\}}$
t2{3,3,3,31,1}
Coxeter-Dynkin diagrams =
=
5-faces76
4-faces636
Cells2160
Faces2880
Edges1440
Vertices160
Vertex figure{3}×{3,4} duoprism
Petrie polygonDodecagon
Coxeter groupsB6, [3,3,3,3,4]
D6, [33,1,1]
Propertiesconvex

The birectified 6-orthoplex can tessellation space in the trirectified 6-cubic honeycomb.

### Alternate names

• birectified hexacross
• birectified hexacontitetrapeton (acronym: brag) (Jonathan Bowers)

### Cartesian coordinates

Cartesian coordinates for the vertices of a rectified hexacross, centered at the origin, edge length ${\displaystyle {\sqrt {2}}\ }$ are all permutations of:

(±1,±1,±1,0,0,0)

### Images

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]

It can also be projected into 3D-dimensions as --> , a dodecahedron envelope.

These polytopes are a part a family of 63 Uniform 6-polytopes generated from the B6 Coxeter plane, including the regular 6-cube or 6-orthoplex.

## Notes

1. Icosidodecahedron from D6 John Baez, January 1, 2015

## References

• H.S.M. Coxeter:
• H.S.M. Coxeter, Regular Polytopes, 3rd Edition, Dover New York, 1973
• Kaleidoscopes: Selected Writings of H.S.M. Coxeter, edited by F. Arthur Sherk, Peter McMullen, Anthony C. Thompson, Asia Ivic Weiss, Wiley-Interscience Publication, 1995, ISBN 978-0-471-01003-6
• (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.
• Klitzing, Richard. "6D uniform polytopes (polypeta)". o3x3o3o3o4o - rag, o3o3x3o3o4o - brag