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Isoclines in the sequence of regular convex 4-polytopes

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Isoclinic rotations relate the regular convex 4-polytopes to each other as a sequence of increasingly 3-spherical convex hulls of isoclinic compounds of their predecessors. A general principle of the relationship of a 4-polytope to its adjacent 4-polytopes in the sequence emerges from a comparison of their characteristic isoclines, the circular helical geodesic paths traced by their vertices under isoclinic rotation. A regular 4-polytope's isocline chords are found in the chords of its predecessor's facets, and its isocline vertex figures are the vertex figures of its successor's facets.

Isoclinic compounds in sequence

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The main sequence of the six regular convex 4-polytopes is evident in their vertex counts,[a] and within that sequence is a subsequence of four with triangular faces representing the major Coxeter symmetry groups: the 5-cell (tetrahedral A4 symmetry), 16-cell (octahedral B4 symmetry), 24-cell (F4 symmetry), and 600-cell (icosahedral H4 symmetry).

[b]

[c]

Regular convex 4-polytopes
5-cell

Hyper-
tetrahedron

16-cell

Hyper-
octahedron

8-cell

Hyper-
cube

24-cell 600-cell

Hyper-
icosahedron

120-cell

Hyper-
dodecahedron

1 {5/2} x 2 1 {8/2}=2{4} x 3 2 {8/2}=2{4} x 3 2 {12/4}=4{3} x 4 20 {30/4}=2{15/2} x 6 100 {30/4}=2{15/2} x 6

Regular convex 4-polytopes

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Sequence of 6 regular convex 4-polytopes
Symmetry group A4 B4 F4 H4
Name 5-cell

Hyper-tetrahedron
5-point

16-cell

Hyper-octahedron
8-point

8-cell

Hyper-cube
16-point

24-cell

Hyper-cuboctahedron
24-point

600-cell

Hyper-icosahedron
120-point

120-cell

Hyper-dodecahedron
600-point

SchlΓ€fli symbol {3, 3, 3} {3, 3, 4} {4, 3, 3} {3, 4, 3} {3, 3, 5} {5, 3, 3}
Coxeter mirrors
Mirror dihedrals 𝝅/3 𝝅/3 𝝅/3 𝝅/2 𝝅/2 𝝅/2 𝝅/3 𝝅/3 𝝅/4 𝝅/2 𝝅/2 𝝅/2 𝝅/4 𝝅/3 𝝅/3 𝝅/2 𝝅/2 𝝅/2 𝝅/3 𝝅/4 𝝅/3 𝝅/2 𝝅/2 𝝅/2 𝝅/3 𝝅/3 𝝅/5 𝝅/2 𝝅/2 𝝅/2 𝝅/5 𝝅/3 𝝅/3 𝝅/2 𝝅/2 𝝅/2
Graph
Vertices[d] 5 tetrahedral 8 octahedral 16 tetrahedral 24 cubical 120 icosahedral 600 tetrahedral
Edges 10 triangular 24 square 32 triangular 96 triangular 720 pentagonal 1200 triangular
Faces 10 triangles 32 triangles 24 squares 96 triangles 1200 triangles 720 pentagons
Cells 5 {3, 3} 16 {3, 3} 8 {4, 3} 24 {3, 4} 600 {3, 3} 120 {5, 3}
Tori 5 {3, 3} 8 {3, 3} x 2 4 {4, 3} x 2 6 {3, 4} x 4 30 {3, 3} x 20 10 {5, 3} x 12
Inscribed 120 in 120-cell 675 in 120-cell 2 16-cells 3 8-cells 25 24-cells 10 600-cells
Great polygons 2 squares x 3[e] 4 rectangles x 4 4 hexagons x 4 12 decagons x 6 100 irregular hexagons x 4
Petrie polygons 1 pentagon x 2 1 octagon x 3 2 octagons x 4 2 dodecagons x 4 4 30-gons x 6 20 30-gons x 4
Long radius
Edge length[f]
Short radius
Area
Volume
4-Content

Notes

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[a]

  1. ↑ 1.0 1.1 The convex regular 4-polytopes can be ordered by size as a measure of 4-dimensional content (hypervolume) for the same radius. Each greater polytope in the sequence is rounder than its predecessor, enclosing more content[1] within the same radius. The 4-simplex (5-cell) is the limit smallest case, and the 120-cell is the largest. Complexity (as measured by comparing configuration matrices or simply the number of vertices) follows the same ordering. This provides an alternative numerical naming scheme for regular polytopes in which the 600-cell is the 120-point 4-polytope: fifth in the ascending sequence that runs from 5-point 4-polytope to 600-point 4-polytope.
  2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named isoclinic geodesic
  3. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named isoclinic compounds
  4. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named 4-polytopes ordered by size and complexity
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Six orthogonal planes of the Cartesian basis
  6. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named edge length of successor

Citations

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  1. ↑ Coxeter 1973, pp. 292-293, Table I(ii): The sixteen regular polytopes {p,q,r} in four dimensions; An invaluable table providing all 20 metrics of each 4-polytope in edge length units. They must be algebraically converted to compare polytopes of unit radius.