Rectified 9-orthoplexes explained

In nine-dimensional geometry, a rectified 9-simplex is a convex uniform 9-polytope, being a rectification of the regular 9-orthoplex.

There are 9 rectifications of the 9-orthoplex. Vertices of the rectified 9-orthoplex are located at the edge-centers of the 9-orthoplex. Vertices of the birectified 9-orthoplex are located in the triangular face centers of the 9-orthoplex. Vertices of the trirectified 9-orthoplex are located in the tetrahedral cell centers of the 9-orthoplex.

These polytopes are part of a family 511 uniform 9-polytopes with BC9 symmetry.

Rectified 9-orthoplex

bgcolor=#e7dcc3 colspan=2Rectified 9-orthoplex
Typeuniform 9-polytope
Schläfli symbolt1
Coxeter-Dynkin diagrams
7-faces
6-faces
5-faces
4-faces
Cells
Faces
Edges2016
Vertices144
Vertex figure7-orthoplex prism
Petrie polygonoctakaidecagon
Coxeter groupsC9, [4,3<sup>7</sup>]
D9, [3<sup>6,1,1</sup>]
Propertiesconvex

The rectified 9-orthoplex is the vertex figure for the demienneractic honeycomb.

or

Alternate names

Construction

There are two Coxeter groups associated with the rectified 9-orthoplex, one with the C9 or [4,3<sup>7</sup>] Coxeter group, and a lower symmetry with two copies of 8-orthoplex facets, alternating, with the D9 or [3<sup>6,1,1</sup>] Coxeter group.

Cartesian coordinates

Cartesian coordinates for the vertices of a rectified 9-orthoplex, centered at the origin, edge length

\sqrt{2}

are all permutations of:

(±1,±1,0,0,0,0,0,0,0)

Root vectors

Its 144 vertices represent the root vectors of the simple Lie group D9. The vertices can be seen in 3 hyperplanes, with the 36 vertices rectified 8-simplexs cells on opposite sides, and 72 vertices of an expanded 8-simplex passing through the center. When combined with the 18 vertices of the 9-orthoplex, these vertices represent the 162 root vectors of the B9 and C9 simple Lie groups.

Images

Birectified 9-orthoplex

Alternate names

Images

Trirectified 9-orthoplex

Alternate names

Images

References

External links

Notes and References

  1. Klitzing (o3x3o3o3o3o3o3o4o - riv)
  2. Klitzing (o3o3x3o3o3o3o3o4o - brav)
  3. Klitzing (o3o3o3x3o3o3o3o4o - tarv)