| 9-cube Enneract |
|
|---|---|
Orthogonal projection inside Petrie polygon Orange vertices are doubled, yellow have 4, and the green center has 8 |
|
| Type | Regular 9-polytope |
| Family | hypercube |
| Schläfli symbol | {4,37} |
| Coxeter-Dynkin diagram | |
| 8-faces | 18 {4,36} |
| 7-faces | 144 {4,35} |
| 6-faces | 672 {4,34} |
| 5-faces | 2016 {4,33} |
| 4-faces | 4032 {4,3,3} |
| Cells | 5376 {4,3} |
| Faces | 4608 {4} |
| Edges | 2304 |
| Vertices | 512 |
| Vertex figure | 8-simplex |
| Petrie polygon | octadecagon |
| Coxeter group | C9, [37,4] |
| Dual | 9-orthoplex |
| Properties | convex |
In geometry, a 9-cube is a nine-dimensional hypercube with 512 vertices, 2304 edges, 4608 square faces, 5376 cubic cells, 4032 tesseract 4-faces, 2016 5-cube 5-faces, 672 6-cube 6-faces, 144 7-cube 7-faces, and 18 8-cube 8-faces.
It can be named by its Schläfli symbol {4,37}, being composed of 3 8-cubes around each 7-face. It is also called an enneract, this name derived from combining the name tesseract (the 4-cube) with enne for nine (dimensions) in Greek. It can also be called a regular octadeca-9-tope or octadecayotton, as a 9 dimensional polytope constructed with 18 regular facets.
It is a part of an infinite family of polytopes, called hypercubes. The dual of an 9-cube can be called a 9-orthoplex, and is a part of the infinite family of cross-polytopes.
Contents |
Cartesian coordinates for the vertices of an 9-cube centered at the origin and edge length 2 are
while the interior of the same consists of all points (x0, x1, x2, x3, x4, x5, x6, x7, x8) with −1 < xi < 1.
This 9-cube graph is an orthogonal projection. This oriention shows columns of vertices positioned a vertex-edge-vertex distance from one vertex on the left to one vertex on the right, and edges attaching adjacent columns of vertices. The number of vertices in each column represents rows in Pascal's triangle, being 1:9:36:84:126:126:84:36:9:1. |
Petrie polygon, skew orthographic projection |
| B9 | B8 | B7 | |||
|---|---|---|---|---|---|
| [18] | [16] | [14] | |||
| B6 | B5 | ||||
| [12] | [10] | ||||
| B4 | B3 | B2 | |||
| [8] | [6] | [4] | |||
Applying an alternation operation, deleting alternating vertices of the enneract, creates another uniform polytope, called a demienneract, (part of an infinite family called demihypercubes), which has 18 demiocteractic and 256 enneazettonic facets.