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1 32 polytope

In 7-dimensional geometry, 1<sub>32</sub> is a uniform polytope, constructed from the E7 group.

Its Coxeter symbol is 1<sub>32</sub>, describing its bifurcating Coxeter-Dynkin diagram, with a single ring on the end of one of the 1-node sequences.

The rectified 1<sub>32</sub> is constructed by points at the mid-edges of the 1<sub>32</sub>.

These polytopes are part of a family of 127 (2<sup>7</sup>−1) convex uniform polytopes in 7 dimensions, made of uniform polytope facets and vertex figures, defined by all permutations of rings in this Coxeter-Dynkin diagram: .

1<sub>32</sub> polytope

This polytope can tessellate 7-dimensional space, with symbol 1<sub>33</sub>, and Coxeter-Dynkin diagram, . It is the Voronoi cell of the dual E<sub>7</sub><sup>*</sup> lattice.

Alternate names

  • Emanuel Lodewijk Elte named it V<sub>576</sub> (for its 576 vertices) in his 1912 listing of semiregular polytopes.
  • Coxeter called it 1<sub>32</sub> for its bifurcating Coxeter-Dynkin diagram, with a single ring on the end of the 1-node branch.
  • Pentacontahexa-hecatonicosihexa-exon (Acronym: lin) - 56-126 facetted polyexon (Jonathan Bowers)

Images

Construction

It is created by a Wythoff construction upon a set of 7 hyperplane mirrors in 7-dimensional space.

The facet information can be extracted from its Coxeter-Dynkin diagram,

Removing the node on the end of the 2-length branch leaves the 6-demicube, 1<sub>31</sub>,

Removing the node on the end of the 3-length branch leaves the 1<sub>22</sub>,

The vertex figure is determined by removing the ringed node and ringing the neighboring node. This makes the birectified 6-simplex, 0<sub>32</sub>,

Seen in a configuration matrix, the element counts can be derived by mirror removal and ratios of Coxeter group orders.

Related polytopes and honeycombs

The 1<sub>32</sub> is third in a dimensional series of uniform polytopes and honeycombs, expressed by Coxeter as 1<sub>3k</sub> series. The next figure is the Euclidean honeycomb 1<sub>33</sub> and the final is a noncompact hyperbolic honeycomb, 1<sub>34</sub>.

Rectified 1<sub>32</sub> polytope

The rectified 1<sub>32</sub> (also called 0<sub>321</sub>) is a rectification of the 1<sub>32</sub> polytope, creating new vertices on the center of edge of the 1<sub>32</sub>. Its vertex figure is a duoprism prism, the product of a regular tetrahedra and triangle, doubled into a prism: {3,3}×{3}×{}.

Alternate names

  • Rectified pentacontahexa-hecatonicosihexa-exon for rectified 56-126 facetted polyexon (Acronym: lanq) (Jonathan Bowers)

Construction

It is created by a Wythoff construction upon a set of 7 hyperplane mirrors in 7-dimensional space. These mirrors are represented by its Coxeter-Dynkin diagram, , and the ring represents the position of the active mirror(s).

Removing the node on the end of the 3-length branch leaves the rectified 1<sub>22</sub> polytope,

Removing the node on the end of the 2-length branch leaves the demihexeract, 1<sub>31</sub>,

Removing the node on the end of the 1-length branch leaves the birectified 6-simplex,

The vertex figure is determined by removing the ringed node and ringing the neighboring node. This makes the tetrahedron-triangle duoprism prism, {3,3}×{3}×{},

Seen in a configuration matrix, the element counts can be derived by mirror removal and ratios of Coxeter group orders.

Images

See also

Notes

References

  • 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, wiley.com,
  • (Paper 24) H.S.M. Coxeter, Regular and Semi-Regular Polytopes III, [Math. Zeit. 200 (1988) 3–45]
  • o3o3o3x *c3o3o3o - lin, o3o3x3o *c3o3o3o - lanq