Uniform 8-polytope

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Graphs of three regular and related uniform polytopes.

8-simplex
Rectified 8-simplex
Truncated 8-simplex
Cantellated 8-simplex
Runcinated 8-simplex
Stericated 8-simplex
Pentellated 8-simplex
Hexicated 8-simplex
Heptellated 8-simplex

8-orthoplex
Rectified 8-orthoplex
Truncated 8-orthoplex
Cantellated 8-orthoplex

Runcinated 8-orthoplex

Hexicated 8-orthoplex

Cantellated 8-cube

Runcinated 8-cube

Stericated 8-cube

Pentellated 8-cube

Hexicated 8-cube

Heptellated 8-cube

8-cube
Rectified 8-cube
Truncated 8-cube

8-demicube
Truncated 8-demicube

Cantellated 8-demicube

Runcinated 8-demicube

Stericated 8-demicube

Pentellated 8-demicube

Hexicated 8-demicube

421

142

241

In

facets
.

A uniform 8-polytope is one which is

vertex-transitive, and constructed from uniform 7-polytope
facets.

Regular 8-polytopes

Regular 8-polytopes can be represented by the

peak
.

There are exactly three such convex regular 8-polytopes:

  1. {3,3,3,3,3,3,3} - 8-simplex
  2. {4,3,3,3,3,3,3} - 8-cube
  3. {3,3,3,3,3,3,4} - 8-orthoplex

There are no nonconvex regular 8-polytopes.

Characteristics

The topology of any given 8-polytope is defined by its

torsion coefficients.[1]

The value of the Euler characteristic used to characterise polyhedra does not generalize usefully to higher dimensions, and is zero for all 8-polytopes, whatever their underlying topology. This inadequacy of the Euler characteristic to reliably distinguish between different topologies in higher dimensions led to the discovery of the more sophisticated Betti numbers.[1]

Similarly, the notion of orientability of a polyhedron is insufficient to characterise the surface twistings of toroidal polytopes, and this led to the use of torsion coefficients.[1]

Uniform 8-polytopes by fundamental Coxeter groups

Uniform 8-polytopes with reflective symmetry can be generated by these four Coxeter groups, represented by permutations of rings of the

Coxeter-Dynkin diagrams
:

# Coxeter group Forms
1 A8 [37] 135
2 BC8 [4,36] 255
3 D8 [35,1,1] 191 (64 unique)
4 E8 [34,2,1] 255

Selected regular and uniform 8-polytopes from each family include:

  1. Simplex family: A8 [37] -
    • 135 uniform 8-polytopes as permutations of rings in the group diagram, including one regular:
      1. {37} - 8-simplex or ennea-9-tope or enneazetton -
  2. orthoplex
    family: B8 [4,36] -
    • 255 uniform 8-polytopes as permutations of rings in the group diagram, including two regular ones:
      1. {4,36} - 8-cube or octeract-
      2. {36,4} - 8-orthoplex or octacross -
  3. Demihypercube D8 family: [35,1,1] -
    • 191 uniform 8-polytopes as permutations of rings in the group diagram, including:
      1. {3,35,1} - 8-demicube or demiocteract, 151 - ; also as h{4,36} .
      2. {3,3,3,3,3,31,1} - 8-orthoplex, 511 -
  4. E-polytope family
    E8 family: [34,1,1] -
    • 255 uniform 8-polytopes as permutations of rings in the group diagram, including:
      1. {3,3,3,3,32,1} -
        421
        ,
      2. {3,34,2} - the uniform
        142
        , ,
      3. {3,3,34,1} - the uniform
        241
        ,

Uniform prismatic forms

There are many

prismatic
families, including:

The A8 family

The A8 family has symmetry of order 362880 (9 factorial).

There are 135 forms based on all permutations of the

Coxeter-Dynkin diagrams
with one or more rings. (128+8-1 cases) These are all enumerated below. Bowers-style acronym names are given in parentheses for cross-referencing.

See also a

Coxeter plane
graphs of these polytopes.

The B8 family

The B8 family has symmetry of order 10321920 (8

Coxeter-Dynkin diagrams
with one or more rings.

See also a

Coxeter plane
graphs of these polytopes.

The D8 family

The D8 family has symmetry of order 5,160,960 (8 factorial x 27).

This family has 191 Wythoffian uniform polytopes, from 3x64-1 permutations of the D8

Coxeter-Dynkin diagram
with one or more rings. 127 (2x64-1) are repeated from the B8 family and 64 are unique to this family, all listed below.

See

list of D8 polytopes
for Coxeter plane graphs of these polytopes.

The E8 family

The E8 family has symmetry order 696,729,600.

There are 255 forms based on all permutations of the

Coxeter-Dynkin diagrams
with one or more rings. Eight forms are shown below, 4 single-ringed, 3 truncations (2 rings), and the final omnitruncation are given below. Bowers-style acronym names are given for cross-referencing.

See also

list of E8 polytopes
for Coxeter plane graphs of this family.

Regular and uniform honeycombs

Coxeter-Dynkin diagram correspondences between families and higher symmetry within diagrams. Nodes of the same color in each row represent identical mirrors. Black nodes are not active in the correspondence.

There are five fundamental affine

Coxeter groups
that generate regular and uniform tessellations in 7-space:

# Coxeter group
Coxeter diagram
Forms
1 [3[8]] 29
2 [4,35,4] 135
3 [4,34,31,1] 191 (64 new)
4 [31,1,33,31,1] 77 (10 new)
5 [33,3,1] 143

Regular and uniform tessellations include:

  • 29 uniquely ringed forms, including:
  • 135 uniquely ringed forms, including:
    • Regular
      7-cube honeycomb
      : {4,34,4} = {4,34,31,1}, =
  • 191 uniquely ringed forms, 127 shared with , and 64 new, including:
    • 7-demicube honeycomb
      : h{4,34,4} = {31,1,34,4}, =
  • , [31,1,33,31,1]: 77 unique ring permutations, and 10 are new, the first Coxeter called a quarter 7-cubic honeycomb.
    • , , , , , , , , ,
  • 143 uniquely ringed forms, including:

Regular and uniform hyperbolic honeycombs

There are no compact hyperbolic Coxeter groups of rank 8, groups that can generate honeycombs with all finite facets, and a finite

4 paracompact hyperbolic Coxeter groups
of rank 8, each generating uniform honeycombs in 7-space as permutations of rings of the Coxeter diagrams.

= [3,3[7]]:
= [31,1,32,32,1]:
= [4,33,32,1]:
= [33,2,2]:

References

  1. ^ a b c Richeson, D.; Euler's Gem: The Polyhedron Formula and the Birth of Topoplogy, Princeton, 2008.
  • T. Gosset: On the Regular and Semi-Regular Figures in Space of n Dimensions, Messenger of Mathematics, Macmillan, 1900
  • A. Boole Stott: Geometrical deduction of semiregular from regular polytopes and space fillings, Verhandelingen of the Koninklijke academy van Wetenschappen width unit Amsterdam, Eerste Sectie 11,1, Amsterdam, 1910
  • H.S.M. Coxeter:
    • H.S.M. Coxeter, M.S. Longuet-Higgins und J.C.P. Miller: Uniform Polyhedra, Philosophical Transactions of the Royal Society of London, Londne, 1954
    • 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,
    • (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]
  • N.W. Johnson: The Theory of Uniform Polytopes and Honeycombs, Ph.D. Dissertation, University of Toronto, 1966
  • Klitzing, Richard. "8D uniform polytopes (polyzetta)".

External links

Family An Bn I2(p) / Dn E6 / E7 / E8 / F4 / G2
Hn
Regular polygon Triangle Square p-gon Hexagon Pentagon
Uniform polyhedron Tetrahedron OctahedronCube Demicube DodecahedronIcosahedron
Uniform polychoron
Pentachoron 16-cellTesseract Demitesseract 24-cell 120-cell600-cell
Uniform 5-polytope 5-simplex 5-orthoplex5-cube 5-demicube
Uniform 6-polytope 6-simplex 6-orthoplex6-cube 6-demicube 122221
Uniform 7-polytope 7-simplex 7-orthoplex7-cube 7-demicube 132231321
Uniform 8-polytope 8-simplex 8-orthoplex8-cube 8-demicube 142241421
Uniform 9-polytope 9-simplex 9-orthoplex9-cube 9-demicube
Uniform 10-polytope 10-simplex 10-orthoplex10-cube 10-demicube
Uniform n-polytope n-simplex n-orthoplexn-cube n-demicube 1k22k1k21 n-pentagonal polytope
Topics:
List of regular polytopes and compounds