In geometry, 1k2 polytope is a uniform polytope in n-dimensions (n = k+4) constructed from the En Coxeter group. The family was named by their Coxeter symbol 1k2 by its bifurcating Coxeter-Dynkin diagram, with a single ring on the end of the 1-node sequence. It can be named by an extended Schläfli symbol {3,3k,2}.
The family starts uniquely as 6-polytopes, but can be extended backwards to include the 5-demicube (demipenteract) in 5-dimensions, and the 4-simplex (5-cell) in 4-dimensions.
Each polytope is constructed from 1k-1,2 and (n-1)-demicube facets. Each has a vertex figure of a {31,n-2,2} polytope is a birectified n-simplex, t2{3n}.
The sequence ends with k=6 (n=10), as an infinite tessellation of 9-dimensional hyperbolic space.
The complete family of 1k2 polytope polytopes are:
n | 1k2 | Petrie polygon projection |
Name Coxeter-Dynkin diagram |
Facets | Elements | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1k-1,2 | (n-1)-demicube | Vertices | Edges | Faces | Cells | 4-faces | 5-faces | 6-faces | 7-faces | ||||
4 | 102 | 120 |
-- | 5 110 |
5 | 10 | 10 |
5 |
|||||
5 | 112 | 121 |
16 120 |
10 111 |
16 | 80 | 160 |
120 |
26 |
||||
6 | 122 | 122 |
27 112 |
27 121 |
72 | 720 | 2160 |
2160 |
702 |
54 |
|||
7 | 132 | 132 |
56 122 |
126 131 |
576 | 10080 | 40320 |
50400 |
23688 |
4284 |
182 |
||
8 | 142 | 142 |
240 132 |
2160 141 |
17280 | 483840 | 2419200 |
3628800 |
2298240 |
725760 |
106080 |
2400 | |
9 | 152 | 152 (8-space tessellation) |
∞ 142 |
∞ 151 |
∞ | ||||||||
10 | 162 | 162 (9-space hyperbolic tessellation) |
∞ 152 |
∞ 161 |
∞ |
Space | Family | / / | ||||
---|---|---|---|---|---|---|
E2 | Uniform tiling | 0[3] | δ3 | hδ3 | qδ3 | Hexagonal |
E3 | Uniform convex honeycomb | 0[4] | δ4 | hδ4 | qδ4 | |
E4 | Uniform 4-honeycomb | 0[5] | δ5 | hδ5 | qδ5 | 24-cell honeycomb |
E5 | Uniform 5-honeycomb | 0[6] | δ6 | hδ6 | qδ6 | |
E6 | Uniform 6-honeycomb | 0[7] | δ7 | hδ7 | qδ7 | 222 |
E7 | Uniform 7-honeycomb | 0[8] | δ8 | hδ8 | qδ8 | 133 • 331 |
E8 | Uniform 8-honeycomb | 0[9] | δ9 | hδ9 | qδ9 | 152 • 251 • 521 |
E9 | Uniform 9-honeycomb | 0[10] | δ10 | hδ10 | qδ10 | |
E10 | Uniform 10-honeycomb | 0[11] | δ11 | hδ11 | qδ11 | |
En-1 | Uniform (n-1)-honeycomb | 0[n] | δn | hδn | qδn | 1k2 • 2k1 • k21 |