Template:Short description Template:Use dmy dates

Example regular polytopes
Regular (2D) polygons
Convex Star
File:Regular pentagon.svg
{5}
File:Star polygon 5-2.svg
{5/2}
Regular (3D) polyhedra
Convex Star
File:Dodecahedron.png
{5,3}
File:Small stellated dodecahedron.png
{5/2,5}
Regular 4D polytopes
Convex Star
File:Schlegel wireframe 120-cell.png
{5,3,3}
File:Ortho solid 010-uniform polychoron p53-t0.png
{5/2,5,3}
Regular 2D tessellations
Euclidean Hyperbolic
File:Uniform tiling 44-t0.svg
{4,4}
File:H2-5-4-dual.svg
{5,4}
Regular 3D tessellations
Euclidean Hyperbolic
File:Cubic honeycomb.png
{4,3,4}
File:Hyperbolic orthogonal dodecahedral honeycomb.png
{5,3,4}

This article lists the regular polytopes in Euclidean, spherical and hyperbolic spaces.

OverviewEdit

This table shows a summary of regular polytope counts by rank.

rowspan=3 Template:Verth Finite Euclidean Hyperbolic rowspan=3 Template:Verth
Compact Paracompact
Convex Star SkewTemplate:Efn<ref name="RegPolyFull">Template:Citation</ref> Convex SkewTemplate:Efn<ref name="RegPolyFull"/> Convex Star Convex
1 1 style="color:#999999; font-size:80%"Template:CNone style="color:#999999; font-size:80%"Template:CNone style="color:#999999; font-size:80%"Template:CNone style="color:#999999; font-size:80%"Template:CNone style="color:#999999; font-size:80%"Template:CNone style="color:#999999; font-size:80%"Template:CNone style="color:#999999; font-size:80%"Template:CNone 1
2 style="color:#999999; font-size:80%"Template:CNone 1 style="color:#999999; font-size:80%"Template:CNone 1 style="color:#999999; font-size:80%"Template:CNone style="color:#999999; font-size:80%"Template:CNone
3 5 4 9 3 3
4 6 10 18 1 7 4 style="color:#999999; font-size:80%"Template:CNone 11
5 3 style="color:#999999; font-size:80%"Template:CNone 3 3 15 5 4 2
6 3 style="color:#999999; font-size:80%"Template:CNone 3 1 7 style="color:#999999; font-size:80%"Template:CNone style="color:#999999; font-size:80%"Template:CNone 5
7+ 3 style="color:#999999; font-size:80%"Template:CNone 3 1 7 style="color:#999999; font-size:80%"Template:CNone style="color:#999999; font-size:80%"Template:CNone style="color:#999999; font-size:80%"Template:CNone

Template:Notelist

There are no Euclidean regular star tessellations in any number of dimensions.

1-polytopesEdit

File:Coxeter node markup1.png A Coxeter diagram represent mirror "planes" as nodes, and puts a ring around a node if a point is not on the plane. A dion { }, Template:CDD, is a point Template:Mvar and its mirror image point Template:Mvar, and the line segment between them.

There is only one polytope of rank 1 (1-polytope), the closed line segment bounded by its two endpoints. Every realization of this 1-polytope is regular. It has the Schläfli symbol { },Template:SfnpTemplate:Sfnp or a Coxeter diagram with a single ringed node, Template:CDD. Norman Johnson calls it a dion<ref>Template:Cite book</ref> and gives it the Schläfli symbol { }.

Although trivial as a polytope, it appears as the edges of polygons and other higher dimensional polytopes.Template:Sfnp It is used in the definition of uniform prisms like Schläfli symbol { }×{p}, or Coxeter diagram Template:CDD as a Cartesian product of a line segment and a regular polygon.Template:Sfnp

2-polytopes (polygons)Edit

The polytopes of rank 2 (2-polytopes) are called polygons. Regular polygons are equilateral and cyclic. A Template:Mvar-gonal regular polygon is represented by Schläfli symbol {p}.

Many sources only consider convex polygons, but star polygons, like the pentagram, when considered, can also be regular. They use the same vertices as the convex forms, but connect in an alternate connectivity which passes around the circle more than once to be completed.

ConvexEdit

The Schläfli symbol {p} represents a [[Regular polygon|regular Template:Mvar-gon]].

Name Triangle
(2-simplex)
Square
(2-orthoplex)
(2-cube)
Pentagon
(2-pentagonal
polytope
)
Hexagon Heptagon Octagon
Schläfli {3} {4} {5} {6} {7} {8}
Symmetry D3, [3] D4, [4] D5, [5] D6, [6] D7, [7] D8, [8]
Coxeter Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD
Image File:Regular triangle.svg File:Regular quadrilateral.svg File:Regular pentagon.svg File:Regular hexagon.svg File:Regular heptagon.svg File:Regular octagon.svg
Name Nonagon
(Enneagon)
Decagon Hendecagon Dodecagon Tridecagon Tetradecagon
Schläfli {9} {10} {11} {12} {13} {14}
Symmetry D9, [9] D10, [10] D11, [11] D12, [12] D13, [13] D14, [14]
Dynkin Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD
Image File:Regular nonagon.svg File:Regular decagon.svg File:Regular hendecagon.svg File:Regular dodecagon.svg File:Regular tridecagon.svg File:Regular tetradecagon.svg
Name Pentadecagon Hexadecagon Heptadecagon Octadecagon Enneadecagon Icosagon p-gon
Schläfli {15} {16} {17} {18} {19} {20} {p}
Symmetry D15, [15] D16, [16] D17, [17] D18, [18] D19, [19] D20, [20] Dp, [p]
Dynkin Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD
Image File:Regular pentadecagon.svg File:Regular hexadecagon.svg File:Regular heptadecagon.svg File:Regular octadecagon.svg File:Regular enneadecagon.svg File:Regular icosagon.svg File:Disk 1.svg

SphericalEdit

The regular digon {2} can be considered to be a degenerate regular polygon. It can be realized non-degenerately in some non-Euclidean spaces, such as on the surface of a sphere or torus. For example, digon can be realised non-degenerately as a spherical lune. A monogon {1} could also be realised on the sphere as a single point with a great circle through it.<ref>Coxeter, Regular Complex Polytopes, p. 9</ref> However, a monogon is not a valid abstract polytope because its single edge is incident to only one vertex rather than two.

Name Monogon Digon
Schläfli symbol {1} {2}
Symmetry D1, [ ] D2, [2]
Coxeter diagram Template:CDD or Template:CDD Template:CDD
Image File:Monogon.svg File:Digon.svg

StarsEdit

There exist infinitely many regular star polytopes in two dimensions, whose Schläfli symbols consist of rational numbers Template:Math. They are called star polygons and share the same vertex arrangements of the convex regular polygons.

In general, for any natural number Template:Mvar, there are regular Template:Mvar-pointed stars with Schläfli symbols Template:Math for all Template:Mvar such that Template:Math (strictly speaking Template:Math) and Template:Mvar and Template:Mvar are coprime (as such, all stellations of a polygon with a prime number of sides will be regular stars). Symbols where Template:Mvar and Template:Mvar are not coprime may be used to represent compound polygons.

Name Pentagram Heptagrams Octagram Enneagrams Decagram ...n-grams
Schläfli {5/2} {7/2} {7/3} {8/3} {9/2} {9/4} {10/3} {p/q}
Symmetry D5, [5] D7, [7] D8, [8] D9, [9], D10, [10] Dp, [p]
Coxeter Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD
Image File:Star polygon 5-2.svg File:Star polygon 7-2.svg File:Star polygon 7-3.svg File:Star polygon 8-3.svg File:Star polygon 9-2.svg File:Star polygon 9-4.svg File:Star polygon 10-3.svg  
Regular star polygons up to 20 sides
File:Regular star polygon 11-2.svg
{11/2}
File:Regular star polygon 11-3.svg
{11/3}
File:Regular star polygon 11-4.svg
{11/4}
File:Regular star polygon 11-5.svg
{11/5}
File:Regular star polygon 12-5.svg
{12/5}
File:Regular star polygon 13-2.svg
{13/2}
File:Regular star polygon 13-3.svg
{13/3}
File:Regular star polygon 13-4.svg
{13/4}
File:Regular star polygon 13-5.svg
{13/5}
File:Regular star polygon 13-6.svg
{13/6}
File:Regular star polygon 14-3.svg
{14/3}
File:Regular star polygon 14-5.svg
{14/5}
File:Regular star polygon 15-2.svg
{15/2}
File:Regular star polygon 15-4.svg
{15/4}
File:Regular star polygon 15-7.svg
{15/7}
File:Regular star polygon 16-3.svg
{16/3}
File:Regular star polygon 16-5.svg
{16/5}
File:Regular star polygon 16-7.svg
{16/7}
File:Regular star polygon 17-2.svg
{17/2}
File:Regular star polygon 17-3.svg
{17/3}
File:Regular star polygon 17-4.svg
{17/4}
File:Regular star polygon 17-5.svg
{17/5}
File:Regular star polygon 17-6.svg
{17/6}
File:Regular star polygon 17-7.svg
{17/7}
File:Regular star polygon 17-8.svg
{17/8}
File:Regular star polygon 18-5.svg
{18/5}
File:Regular star polygon 18-7.svg
{18/7}
File:Regular star polygon 19-2.svg
{19/2}
File:Regular star polygon 19-3.svg
{19/3}
File:Regular star polygon 19-4.svg
{19/4}
File:Regular star polygon 19-5.svg
{19/5}
File:Regular star polygon 19-6.svg
{19/6}
File:Regular star polygon 19-7.svg
{19/7}
File:Regular star polygon 19-8.svg
{19/8}
File:Regular star polygon 19-9.svg
{19/9}
File:Regular star polygon 20-3.svg
{20/3}
File:Regular star polygon 20-7.svg
{20/7}
File:Regular star polygon 20-9.svg
{20/9}

Star polygons that can only exist as spherical tilings, similarly to the monogon and digon, may exist (for example: {3/2}, {5/3}, {5/4}, {7/4}, {9/5}), however these have not been studied in detail.

There also exist failed star polygons, such as the piangle, which do not cover the surface of a circle finitely many times.<ref name=":0">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Skew polygonsEdit

In addition to the planar regular polygons there are infinitely many regular skew polygons. Skew polygons can be created via the blending operation.

The blend of two polygons Template:Mvar and Template:Mvar, written Template:Math, can be constructed as follows:

  1. take the cartesian product of their vertices Template:Math.
  2. add edges Template:Math where Template:Math is an edge of Template:Mvar and Template:Math is an edge of Template:Mvar.
  3. select an arbitrary connected component of the result.

Alternatively, the blend is the polygon Template:Math where Template:Mvar and Template:Mvar are the generating mirrors of Template:Mvar and Template:Mvar placed in orthogonal subspaces.Template:Sfn The blending operation is commutative, associative and idempotent.

Every regular skew polygon can be expressed as the blend of a uniqueTemplate:Efn set of planar polygons.Template:Sfn If Template:Mvar and Template:Mvar share no factors then Template:Math.

In 3 spaceEdit

The regular finite polygons in 3 dimensions are exactly the blends of the planar polygons (dimension 2) with the digon (dimension 1). They have vertices corresponding to a prism (Template:Math where Template:Mvar is odd) or an antiprism (Template:Math where Template:Mvar is even). All polygons in 3 space have an even number of vertices and edges.

Several of these appear as the Petrie polygons of regular polyhedra.

In 4 spaceEdit

The regular finite polygons in 4 dimensions are exactly the polygons formed as a blend of two distinct planar polygons. They have vertices lying on a Clifford torus and related by a Clifford displacement. Unlike 3-dimensional polygons, skew polygons on double rotations can include an odd-number of sides.

3-polytopes (polyhedra)Edit

Polytopes of rank 3 are called polyhedra:

A regular polyhedron with Schläfli symbol Template:Math, Coxeter diagrams Template:CDD, has a regular face type Template:Math, and regular vertex figure Template:Math.

A vertex figure (of a polyhedron) is a polygon, seen by connecting those vertices which are one edge away from a given vertex. For regular polyhedra, this vertex figure is always a regular (and planar) polygon.

Existence of a regular polyhedron Template:Math is constrained by an inequality, related to the vertex figure's angle defect: <math display=block> \begin{align} & \frac{1}{p} + \frac{1}{q} > \frac{1}{2} : \text{Polyhedron (existing in Euclidean 3-space)} \\[6pt] & \frac{1}{p} + \frac{1}{q} = \frac{1}{2} : \text{Euclidean plane tiling} \\[6pt] & \frac{1}{p} + \frac{1}{q} < \frac{1}{2} : \text{Hyperbolic plane tiling} \end{align} </math>

By enumerating the permutations, we find five convex forms, four star forms and three plane tilings, all with polygons Template:Math and Template:Math limited to: {3}, {4}, {5}, {5/2}, and {6}.

Beyond Euclidean space, there is an infinite set of regular hyperbolic tilings.

ConvexEdit

The five convex regular polyhedra are called the Platonic solids. The vertex figure is given with each vertex count. All these polyhedra have an Euler characteristic (χ) of 2.

Name Schläfli
Template:Math
Coxeter
Template:CDD
Image
(solid)
Image
(sphere)
Faces
Template:Math
Edges Vertices
Template:Math
Symmetry Dual
Tetrahedron
(3-simplex)
{3,3} Template:CDD File:Polyhedron 4b.png File:Uniform tiling 332-t2.svg 4
{3}
6 4
{3}
Td
[3,3]
(*332)
(self)
Hexahedron
Cube
(3-cube)
{4,3} Template:CDD File:Polyhedron 6.png File:Uniform tiling 432-t0.png 6
{4}
12 8
{3}
Oh
[4,3]
(*432)
Octahedron
Octahedron
(3-orthoplex)
{3,4} Template:CDD File:Polyhedron 8.png File:Uniform tiling 432-t2.png 8
{3}
12 6
{4}
Oh
[4,3]
(*432)
Cube
Dodecahedron {5,3} Template:CDD File:Polyhedron 12.png File:Uniform tiling 532-t0.png 12
{5}
30 20
{3}
Ih
[5,3]
(*532)
Icosahedron
Icosahedron {3,5} Template:CDD File:Polyhedron 20.png File:Uniform tiling 532-t2.png 20
{3}
30 12
{5}
Ih
[5,3]
(*532)
Dodecahedron

SphericalEdit

In spherical geometry, regular spherical polyhedra (tilings of the sphere) exist that would otherwise be degenerate as polytopes. These are the hosohedra {2,n} and their dual dihedra {n,2}. Coxeter calls these cases "improper" tessellations.Template:Sfnp

The first few cases (n from 2 to 6) are listed below.

Hosohedra
Name Schläfli
{2,p}
Coxeter
diagram
Image
(sphere)
Faces
{2}π/p
Edges Vertices
{p}
Symmetry Dual
Digonal hosohedron {2,2} Template:CDD File:Spherical digonal hosohedron.svg 2
{2}π/2
2 2
{2}π/2
D2h
[2,2]
(*222)
Self
Trigonal hosohedron {2,3} Template:CDD File:Spherical trigonal hosohedron.svg 3
{2}π/3
3 2
{3}
D3h
[2,3]
(*322)
Trigonal dihedron
Square hosohedron {2,4} Template:CDD File:Spherical square hosohedron.svg 4
{2}π/4
4 2
{4}
D4h
[2,4]
(*422)
Square dihedron
Pentagonal hosohedron {2,5} Template:CDD File:Spherical pentagonal hosohedron.svg 5
{2}π/5
5 2
{5}
D5h
[2,5]
(*522)
Pentagonal dihedron
Hexagonal hosohedron {2,6} Template:CDD File:Spherical hexagonal hosohedron.svg 6
{2}π/6
6 2
{6}
D6h
[2,6]
(*622)
Hexagonal dihedron
Dihedra
Name Schläfli
{p,2}
Coxeter
diagram
Image
(sphere)
Faces
{p}
Edges Vertices
{2}
Symmetry Dual
Digonal dihedron {2,2} Template:CDD File:Digonal dihedron.png 2
{2}π/2
2 2
{2}π/2
D2h
[2,2]
(*222)
Self
Trigonal dihedron {3,2} Template:CDD File:Trigonal dihedron.png 2
{3}
3 3
{2}π/3
D3h
[3,2]
(*322)
Trigonal hosohedron
Square dihedron {4,2} Template:CDD File:Tetragonal dihedron.png 2
{4}
4 4
{2}π/4
D4h
[4,2]
(*422)
Square hosohedron
Pentagonal dihedron {5,2} Template:CDD File:Pentagonal dihedron.png 2
{5}
5 5
{2}π/5
D5h
[5,2]
(*522)
Pentagonal hosohedron
Hexagonal dihedron {6,2} Template:CDD File:Hexagonal dihedron.png 2
{6}
6 6
{2}π/6
D6h
[6,2]
(*622)
Hexagonal hosohedron

Star-dihedra and hosohedra Template:Math and Template:Math also exist for any star polygon Template:Math.

StarsEdit

The regular star polyhedra are called the Kepler–Poinsot polyhedra and there are four of them, based on the vertex arrangements of the dodecahedron {5,3} and icosahedron {3,5}:

As spherical tilings, these star forms overlap the sphere multiple times, called its density, being 3 or 7 for these forms. The tiling images show a single spherical polygon face in yellow.

Name Image
(skeletonic)
Image
(solid)
Image
(sphere)
Stellation
diagram
Schläfli
Template:Math and
Coxeter
Faces
Template:Math
Edges Vertices
Template:Math
verf.
χ Density Symmetry Dual
Small stellated dodecahedron File:Skeleton St12, size m.png File:Small stellated dodecahedron (gray with yellow face).svg File:Small stellated dodecahedron tiling.png File:First stellation of dodecahedron facets.svg {5/2,5}
Template:CDD
12
{5/2}
File:Star polygon 5-2.svg
30 12
{5}
File:Regular pentagon.svg
−6 3 Ih
[5,3]
(*532)
Great dodecahedron
Great dodecahedron File:Skeleton Gr12, size m.png File:Great dodecahedron (gray with yellow face).svg File:Great dodecahedron tiling.svg File:Second stellation of dodecahedron facets.svg {5,5/2}
Template:CDD
12
{5}
File:Regular pentagon.svg
30 12
{5/2}
File:Star polygon 5-2.svg
−6 3 Ih
[5,3]
(*532)
Small stellated dodecahedron
Great stellated dodecahedron File:Skeleton GrSt12, size s.png File:Great stellated dodecahedron (gray with yellow face).svg File:Great stellated dodecahedron tiling.svg File:Third stellation of dodecahedron facets.svg {5/2,3}
Template:CDD
12
{5/2}
File:Star polygon 5-2.svg
30 20
{3}
File:Regular triangle.svg
2 7 Ih
[5,3]
(*532)
Great icosahedron
Great icosahedron File:Skeleton Gr20, size m.png File:Great icosahedron (gray with yellow face).svg File:Great icosahedron tiling.svg File:Great icosahedron stellation facets.svg {3,5/2}
Template:CDD
20
{3}
File:Regular triangle.svg
30 12
{5/2}
File:Star polygon 5-2.svg
2 7 Ih
[5,3]
(*532)
Great stellated dodecahedron

There are infinitely many failed star polyhedra. These are also spherical tilings with star polygons in their Schläfli symbols, but they do not cover a sphere finitely many times. Some examples are {5/2,4}, {5/2,9}, {7/2,3}, {5/2,5/2}, {7/2,7/3}, {4,5/2}, and {3,7/3}.

Skew polyhedraEdit

Template:Expand section Regular skew polyhedra are generalizations to the set of regular polyhedron which include the possibility of nonplanar vertex figures.

For 4-dimensional skew polyhedra, Coxeter offered a modified Schläfli symbol {l,m|n} for these figures, with {l,m} implying the vertex figure, m l-gons around a vertex, and Template:Mvar-gonal holes. Their vertex figures are skew polygons, zig-zagging between two planes.

The regular skew polyhedra, represented by {l,m|n}, follow this equation:

<math display="block">2 \sin\left(\frac{\pi}{l}\right) \sin\left(\frac{\pi}{m}\right) = \cos\left(\frac{\pi}{n}\right)</math>

Four of them can be seen in 4-dimensions as a subset of faces of four regular 4-polytopes, sharing the same vertex arrangement and edge arrangement:

File:4-simplex t03.svg File:4-simplex t12.svg File:24-cell t03 F4.svg File:24-cell t12 F4.svg
{4, 6 Template:Pipe 3} {6, 4 Template:Pipe 3} {4, 8 Template:Pipe 3} {8, 4 Template:Pipe 3}

4-polytopesEdit

Regular 4-polytopes with Schläfli symbol <math>\{p,q,r\}</math> have cells of type <math>\{p,q\}</math>, faces of type <math>\{p\}</math>, edge figures <math>\{r\}</math>, and vertex figures <math>\{q,r\}</math>.

  • A vertex figure (of a 4-polytope) is a polyhedron, seen by the arrangement of neighboring vertices around a given vertex. For regular 4-polytopes, this vertex figure is a regular polyhedron.
  • An edge figure is a polygon, seen by the arrangement of faces around an edge. For regular 4-polytopes, this edge figure will always be a regular polygon.

The existence of a regular 4-polytope <math>\{p,q,r\}</math> is constrained by the existence of the regular polyhedra <math>\{p,q\}, \{q,r\}</math>. A suggested name for 4-polytopes is "polychoron".<ref>Template:Cite conference</ref>

Each will exist in a space dependent upon this expression:

<math>\sin \left ( \frac{\pi}{p} \right ) \sin \left(\frac{\pi}{r}\right) - \cos\left(\frac{\pi}{q}\right)</math>
<math>> 0</math> : Hyperspherical 3-space honeycomb or 4-polytope
<math>= 0</math> : Euclidean 3-space honeycomb
<math>< 0</math> : Hyperbolic 3-space honeycomb

These constraints allow for 21 forms: 6 are convex, 10 are nonconvex, one is a Euclidean 3-space honeycomb, and 4 are hyperbolic honeycombs.

The Euler characteristic <math>\chi</math> for convex 4-polytopes is zero: <math>\chi = V+F-E-C = 0</math>

ConvexEdit

The 6 convex regular 4-polytopes are shown in the table below. All these 4-polytopes have an Euler characteristic (χ) of 0.

Name
Schläfli
{p,q,r}
Coxeter
Template:CDD
Cells
{p,q}
Faces
{p}
Edges
{r}
Vertices
{q,r}
Dual
{r,q,p}
5-cell
(4-simplex)
{3,3,3} Template:CDD 5
{3,3}
10
{3}
10
{3}
5
{3,3}
(self)
8-cell
(4-cube)
(Tesseract)
{4,3,3} Template:CDD 8
{4,3}
24
{4}
32
{3}
16
{3,3}
16-cell
16-cell
(4-orthoplex)
{3,3,4} Template:CDD 16
{3,3}
32
{3}
24
{4}
8
{3,4}
Tesseract
24-cell {3,4,3} Template:CDD 24
{3,4}
96
{3}
96
{3}
24
{4,3}
(self)
120-cell {5,3,3} Template:CDD 120
{5,3}
720
{5}
1200
{3}
600
{3,3}
600-cell
600-cell {3,3,5} Template:CDD 600
{3,3}
1200
{3}
720
{5}
120
{3,5}
120-cell
5-cell 8-cell 16-cell 24-cell 120-cell 600-cell
{3,3,3} {4,3,3} {3,3,4} {3,4,3} {5,3,3} {3,3,5}
Wireframe (Petrie polygon) skew orthographic projections
File:Complete graph K5.svg File:4-cube graph.svg File:4-orthoplex.svg File:24-cell graph F4.svg File:Cell120Petrie.svg File:Cell600Petrie.svg
Solid orthographic projections
File:Tetrahedron.png
tetrahedral
envelope
(cell/
vertex-centered)
File:Hexahedron.png
cubic envelope
(cell-centered)
File:16-cell ortho cell-centered.png
cubic envelope
(cell-centered)
File:Ortho solid 24-cell.png
cuboctahedral
envelope

(cell-centered)
File:Ortho solid 120-cell.png
truncated rhombic
triacontahedron
envelope

(cell-centered)
File:Ortho solid 600-cell.png
Pentakis
icosidodecahedral

envelope
(vertex-centered)
Wireframe Schlegel diagrams (Perspective projection)
File:Schlegel wireframe 5-cell.png
(cell-centered)
File:Schlegel wireframe 8-cell.png
(cell-centered)
File:Schlegel wireframe 16-cell.png
(cell-centered)
File:Schlegel wireframe 24-cell.png
(cell-centered)
File:Schlegel wireframe 120-cell.png
(cell-centered)
File:Schlegel wireframe 600-cell vertex-centered.png
(vertex-centered)
Wireframe stereographic projections (Hyperspherical)
File:Stereographic polytope 5cell.png File:Stereographic polytope 8cell.png File:Stereographic polytope 16cell.png File:Stereographic polytope 24cell.png File:Stereographic polytope 120cell.png File:Stereographic polytope 600cell.png

SphericalEdit

Di-4-topes and hoso-4-topes exist as regular tessellations of the 3-sphere.

Regular di-4-topes (2 facets) include: {3,3,2}, {3,4,2}, {4,3,2}, {5,3,2}, {3,5,2}, {p,2,2}, and their hoso-4-tope duals (2 vertices): {2,3,3}, {2,4,3}, {2,3,4}, {2,3,5}, {2,5,3}, {2,2,p}. 4-polytopes of the form {2,p,2} are the same as {2,2,p}. There are also the cases {p,2,q} which have dihedral cells and hosohedral vertex figures.

Regular hoso-4-topes as 3-sphere honeycombs
Schläfli
{2,p,q}
Coxeter
Template:CDD
Cells
{2,p}π/q
Faces
{2}π/p,π/q
Edges Vertices Vertex figure
{p,q}
Symmetry Dual
{2,3,3} Template:CDD 4
{2,3}π/3
File:Spherical trigonal hosohedron.svg
6
{2}π/3,π/3
4 2 {3,3}
File:Uniform tiling 332-t0-1-.svg
[2,3,3] {3,3,2}
{2,4,3} Template:CDD 6
{2,4}π/3
File:Spherical square hosohedron.svg
12
{2}π/4,π/3
8 2 {4,3}
File:Uniform tiling 432-t0.png
[2,4,3] {3,4,2}
{2,3,4} Template:CDD 8
{2,3}π/4
File:Spherical trigonal hosohedron.svg
12
{2}π/3,π/4
6 2 {3,4}
File:Uniform tiling 432-t2.png
[2,4,3] {4,3,2}
{2,5,3} Template:CDD 12
{2,5}π/3
File:Spherical trigonal hosohedron.svg
30
{2}π/5,π/3
20 2 {5,3}
File:Uniform tiling 532-t0.png
[2,5,3] {3,5,2}
{2,3,5} Template:CDD 20
{2,3}π/5
File:Spherical pentagonal hosohedron.svg
30
{2}π/3,π/5
12 2 {3,5}
File:Uniform tiling 532-t2.png
[2,5,3] {5,3,2}

StarsEdit

There are ten regular star 4-polytopes, which are called the Schläfli–Hess 4-polytopes. Their vertices are based on the convex 120-cell {5,3,3} and 600-cell {3,3,5}.

Ludwig Schläfli found four of them and skipped the last six because he would not allow forms that failed the Euler characteristic on cells or vertex figures (for zero-hole tori: F+V−E=2). Edmund Hess (1843–1903) completed the full list of ten in his German book Einleitung in die Lehre von der Kugelteilung mit besonderer Berücksichtigung ihrer Anwendung auf die Theorie der Gleichflächigen und der gleicheckigen Polyeder (1883)[1].

There are 4 unique edge arrangements and 7 unique face arrangements from these 10 regular star 4-polytopes, shown as orthogonal projections:

Name
Wireframe Solid Schläfli
{p, q, r}
Coxeter
Cells
{p, q}
Faces
{p}
Edges
{r}
Vertices
{q, r}
Density χ Symmetry group Dual
{r, q,p}
Icosahedral 120-cell
(faceted 600-cell)
File:Schläfli-Hess polychoron-wireframe-3.png File:Ortho solid 007-uniform polychoron 35p-t0.png {3,5,5/2}
Template:CDD
120
{3,5}
File:Icosahedron.png
1200
{3}
File:Regular triangle.svg
720
{5/2}
File:Star polygon 5-2.svg
120
{5,5/2}
File:Great dodecahedron.png
4 480 H4
[5,3,3]
Small stellated 120-cell
Small stellated 120-cell File:Schläfli-Hess polychoron-wireframe-2.png File:Ortho solid 010-uniform polychoron p53-t0.png {5/2,5,3}
Template:CDD
120
{5/2,5}
File:Small stellated dodecahedron.png
720
{5/2}
File:Star polygon 5-2.svg
1200
{3}
File:Regular triangle.svg
120
{5,3}
File:Dodecahedron.png
4 −480 H4
[5,3,3]
Icosahedral 120-cell
Great 120-cell File:Schläfli-Hess polychoron-wireframe-3.png File:Ortho solid 008-uniform polychoron 5p5-t0.png {5,5/2,5}
Template:CDD
120
{5,5/2}
File:Great dodecahedron.png
720
{5}
File:Regular pentagon.svg
720
{5}
File:Regular pentagon.svg
120
{5/2,5}
File:Small stellated dodecahedron.png
6 0 H4
[5,3,3]
Self-dual
Grand 120-cell File:Schläfli-Hess polychoron-wireframe-3.png File:Ortho solid 009-uniform polychoron 53p-t0.png {5,3,5/2}
Template:CDD
120
{5,3}
File:Dodecahedron.png
720
{5}
File:Regular pentagon.svg
720
{5/2}
File:Star polygon 5-2.svg
120
{3,5/2}
File:Great icosahedron.png
20 0 H4
[5,3,3]
Great stellated 120-cell
Great stellated 120-cell File:Schläfli-Hess polychoron-wireframe-4.png File:Ortho solid 012-uniform polychoron p35-t0.png {5/2,3,5}
Template:CDD
120
{5/2,3}
File:Great stellated dodecahedron.png
720
{5/2}
File:Star polygon 5-2.svg
720
{5}
File:Regular pentagon.svg
120
{3,5}
File:Icosahedron.png
20 0 H4
[5,3,3]
Grand 120-cell
Grand stellated 120-cell File:Schläfli-Hess polychoron-wireframe-4.png File:Ortho solid 013-uniform polychoron p5p-t0.png {5/2,5,5/2}
Template:CDD
120
{5/2,5}
File:Small stellated dodecahedron.png
720
{5/2}
File:Star polygon 5-2.svg
720
{5/2}
File:Star polygon 5-2.svg
120
{5,5/2}
File:Great dodecahedron.png
66 0 H4
[5,3,3]
Self-dual
Great grand 120-cell File:Schläfli-Hess polychoron-wireframe-2.png File:Ortho solid 011-uniform polychoron 53p-t0.png {5,5/2,3}
Template:CDD
120
{5,5/2}
File:Great dodecahedron.png
720
{5}
File:Regular pentagon.svg
1200
{3}
File:Regular triangle.svg
120
{5/2,3}
File:Great stellated dodecahedron.png
76 −480 H4
[5,3,3]
Great icosahedral 120-cell
Great icosahedral 120-cell
(great faceted 600-cell)
File:Schläfli-Hess polychoron-wireframe-4.png File:Ortho solid 014-uniform polychoron 3p5-t0.png {3,5/2,5}
Template:CDD
120
{3,5/2}
File:Great icosahedron.png
1200
{3}
File:Regular triangle.svg
720
{5}
File:Regular pentagon.svg
120
{5/2,5}
File:Small stellated dodecahedron.png
76 480 H4
[5,3,3]
Great grand 120-cell
Grand 600-cell File:Schläfli-Hess polychoron-wireframe-4.png File:Ortho solid 015-uniform polychoron 33p-t0.png {3,3,5/2}
Template:CDD
600
{3,3}
File:Tetrahedron.png
1200
{3}
File:Regular triangle.svg
720
{5/2}
File:Star polygon 5-2.svg
120
{3,5/2}
File:Great icosahedron.png
191 0 H4
[5,3,3]
Great grand stellated 120-cell
Great grand stellated 120-cell File:Schläfli-Hess polychoron-wireframe-1.png File:Ortho solid 016-uniform polychoron p33-t0.png {5/2,3,3}
Template:CDD
120
{5/2,3}
File:Great stellated dodecahedron.png
720
{5/2}
File:Star polygon 5-2.svg
1200
{3}
File:Regular triangle.svg
600
{3,3}
File:Tetrahedron.png
191 0 H4
[5,3,3]
Grand 600-cell

There are 4 failed potential regular star 4-polytopes permutations: {3,5/2,3}, {4,3,5/2}, {5/2,3,4}, {5/2,3,5/2}. Their cells and vertex figures exist, but they do not cover a hypersphere with a finite number of repetitions.

Skew 4-polytopesEdit

Template:Expand section In addition to the 16 planar 4-polytopes above there are 18 finite skew polytopes.Template:Sfnp One of these is obtained as the Petrial of the tesseract, and the other 17 can be formed by applying the kappa operation to the planar polytopes and the Petrial of the tesseract.

Ranks 5 and higherEdit

5-polytopes can be given the symbol <math>\{p,q,r,s\}</math> where <math>\{p,q,r\}</math> is the 4-face type, <math>\{p,q\}</math> is the cell type, <math>\{p\}</math> is the face type, and <math>\{s\}</math> is the face figure, <math>\{r,s\}</math> is the edge figure, and <math>\{q,r,s\}</math> is the vertex figure.

A vertex figure (of a 5-polytope) is a 4-polytope, seen by the arrangement of neighboring vertices to each vertex.
An edge figure (of a 5-polytope) is a polyhedron, seen by the arrangement of faces around each edge.
A face figure (of a 5-polytope) is a polygon, seen by the arrangement of cells around each face.

A regular 5-polytope <math>\{p,q,r,s\}</math> exists only if <math>\{p,q,r\}</math> and <math>\{q,r,s\}</math> are regular 4-polytopes.

The space it fits in is based on the expression:

<math>\frac{\cos^2\left(\frac{\pi}{q}\right)}{\sin^2\left(\frac{\pi}{p}\right)} + \frac{\cos^2\left(\frac{\pi}{r}\right)}{\sin^2\left(\frac{\pi}{s}\right)}</math>
<math>< 1</math> : Spherical 4-space tessellation or 5-space polytope
<math>= 1</math> : Euclidean 4-space tessellation
<math>> 1</math> : hyperbolic 4-space tessellation

Enumeration of these constraints produce 3 convex polytopes, no star polytopes, 3 tessellations of Euclidean 4-space, and 5 tessellations of paracompact hyperbolic 4-space. The only non-convex regular polytopes for ranks 5 and higher are skews.

ConvexEdit

In dimensions 5 and higher, there are only three kinds of convex regular polytopes.Template:Sfnp

Name Schläfli
Symbol
{p1,...,pn−1}
Coxeter k-faces Facet
type
Vertex
figure
Dual
n-simplex {3n−1} Template:CDD...Template:CDD <math>{{n+1} \choose {k+1}}</math> {3n−2} {3n−2} Self-dual
n-cube {4,3n−2} Template:CDD...Template:CDD <math>2^{n-k}{n \choose k}</math> {4,3n−3} {3n−2} n-orthoplex
n-orthoplex {3n−2,4} Template:CDD...Template:CDD <math>2^{k+1}{n \choose {k+1}}</math> {3n−2} {3n−3,4} n-cube

There are also improper cases where some numbers in the Schläfli symbol are 2. For example, {p,q,r,...2} is an improper regular spherical polytope whenever {p,q,r...} is a regular spherical polytope, and {2,...p,q,r} is an improper regular spherical polytope whenever {...p,q,r} is a regular spherical polytope. Such polytopes may also be used as facets, yielding forms such as {p,q,...2...y,z}.

5 dimensionsEdit

Name Schläfli
Symbol
{p,q,r,s}
Coxeter
Facets
{p,q,r}
Cells
{p,q}
Faces
{p}
Edges Vertices Face
figure
{s}
Edge
figure
{r,s}
Vertex
figure

{q,r,s}
5-simplex {3,3,3,3}
Template:CDD
6
{3,3,3}
15
{3,3}
20
{3}
15 6 {3} {3,3} {3,3,3}
5-cube {4,3,3,3}
Template:CDD
10
{4,3,3}
40
{4,3}
80
{4}
80 32 {3} {3,3} {3,3,3}
5-orthoplex {3,3,3,4}
Template:CDD
32
{3,3,3}
80
{3,3}
80
{3}
40 10 {4} {3,4} {3,3,4}
File:5-simplex t0.svg
5-simplex
File:5-cube graph.svg
5-cube
File:5-orthoplex.svg
5-orthoplex

6 dimensionsEdit

Name Schläfli Vertices Edges Faces Cells 4-faces 5-faces χ
6-simplex {3,3,3,3,3} 7 21 35 35 21 7 0
6-cube {4,3,3,3,3} 64 192 240 160 60 12 0
6-orthoplex {3,3,3,3,4} 12 60 160 240 192 64 0
File:6-simplex t0.svg
6-simplex
File:6-cube graph.svg
6-cube
File:6-orthoplex.svg
6-orthoplex

7 dimensionsEdit

Name Schläfli Vertices Edges Faces Cells 4-faces 5-faces 6-faces χ
7-simplex {3,3,3,3,3,3} 8 28 56 70 56 28 8 2
7-cube {4,3,3,3,3,3} 128 448 672 560 280 84 14 2
7-orthoplex {3,3,3,3,3,4} 14 84 280 560 672 448 128 2
File:7-simplex t0.svg
7-simplex
File:7-cube graph.svg
7-cube
File:7-orthoplex.svg
7-orthoplex

8 dimensionsEdit

Name Schläfli Vertices Edges Faces Cells 4-faces 5-faces 6-faces 7-faces χ
8-simplex {3,3,3,3,3,3,3} 9 36 84 126 126 84 36 9 0
8-cube {4,3,3,3,3,3,3} 256 1024 1792 1792 1120 448 112 16 0
8-orthoplex {3,3,3,3,3,3,4} 16 112 448 1120 1792 1792 1024 256 0
File:8-simplex t0.svg
8-simplex
File:8-cube.svg
8-cube
File:8-orthoplex.svg
8-orthoplex

9 dimensionsEdit

Name Schläfli Vertices Edges Faces Cells 4-faces 5-faces 6-faces 7-faces 8-faces χ
9-simplex {38} 10 45 120 210 252 210 120 45 10 2
9-cube {4,37} 512 2304 4608 5376 4032 2016 672 144 18 2
9-orthoplex {37,4} 18 144 672 2016 4032 5376 4608 2304 512 2
File:9-simplex t0.svg
9-simplex
File:9-cube.svg
9-cube
File:9-orthoplex.svg
9-orthoplex

10 dimensionsEdit

Name Schläfli Vertices Edges Faces Cells 4-faces 5-faces 6-faces 7-faces 8-faces 9-faces χ
10-simplex {39} 11 55 165 330 462 462 330 165 55 11 0
10-cube {4,38} 1024 5120 11520 15360 13440 8064 3360 960 180 20 0
10-orthoplex {38,4} 20 180 960 3360 8064 13440 15360 11520 5120 1024 0
File:10-simplex t0.svg
10-simplex
File:10-cube.svg
10-cube
File:10-orthoplex.svg
10-orthoplex

Star polytopesEdit

There are no regular star polytopes of rank 5 or higher, with the exception of degenerate polytopes created by the star product of lower rank star polytopes. Template:Abbr hosotopes and ditopes.

Regular projective polytopesEdit

A projective regular Template:Math-polytope exists when an original regular Template:Mvar-spherical tessellation, {p,q,...}, is centrally symmetric. Such a polytope is named hemi-{p,q,...}, and contain half as many elements. Coxeter gives a symbol {p,q,...}/2, while McMullen writes {p,q,...}h/2 with h as the coxeter number.Template:Sfnp

Even-sided regular polygons have hemi-2n-gon projective polygons, {2p}/2.

There are 4 regular projective polyhedra related to 4 of 5 Platonic solids.

The hemi-cube and hemi-octahedron generalize as hemi-[[hypercube|Template:Mvar-cubes]] and hemi-Template:Mvar-orthoplexes to any rank.

Regular projective polyhedraEdit

rank 3 regular hemi-polytopes
Name Coxeter
McMullen
Image Faces Edges Vertices χ skeleton graph
Hemi-cube {4,3}/2
{4,3}3
File:Hemicube.svg 3 6 4 1 K4
Hemi-octahedron {3,4}/2
{3,4}3
File:Hemi-octahedron2.png 4 6 3 1 Double-edged K3
Hemi-dodecahedron {5,3}/2
{5,3}5
File:Hemi-dodecahedron.png 6 15 10 1 G(5,2)
Hemi-icosahedron {3,5}/2
{3,5}5
File:Hemi-icosahedron2.png 10 15 6 1 K6

Regular projective 4-polytopesEdit

5 of 6 convex regular 4-polytopes are centrally symmetric generating projective 4-polytopes. The 3 special cases are hemi-24-cell, hemi-600-cell, and hemi-120-cell.

Rank 4 regular hemi-polytopes
Name Coxeter
symbol
McMullen
Symbol
Cells Faces Edges Vertices χ Skeleton graph
Hemitesseract {4,3,3}/2 {4,3,3}4 4 12 16 8 0 K4,4
Hemi-16-cell {3,3,4}/2 {3,3,4}4 8 16 12 4 0 double-edged K4
Hemi-24-cell {3,4,3}/2 {3,4,3}6 12 48 48 12 0
Hemi-120-cell {5,3,3}/2 {5,3,3}15 60 360 600 300 0
Hemi-600-cell {3,3,5}/2 {3,3,5}15 300 600 360 60 0

Regular projective 5-polytopesEdit

Only 2 of 3 regular spherical polytopes are centrally symmetric for ranks 5 or higher. The corresponding regular projective polytopes are the hemi versions of the regular hypercube and orthoplex. They are tabulated below for rank 5, for example:

Name Schläfli 4-faces Cells Faces Edges Vertices χ Skeleton graph
hemi-penteract {4,3,3,3}/2 5 20 40 40 16 1 Tesseract skeleton
+ 8 central diagonals
hemi-pentacross {3,3,3,4}/2 16 40 40 20 5 1 double-edged K5

ApeirotopesEdit

An apeirotope or infinite polytope is a polytope which has infinitely many facets. An Template:Mvar-apeirotope is an infinite Template:Mvar-polytope: a 2-apeirotope or apeirogon is an infinite polygon, a 3-apeirotope or apeirohedron is an infinite polyhedron, etc.

There are two main geometric classes of apeirotope:<ref>Template:Cite journal</ref>

2-apeirotopes (apeirogons)Edit

The straight apeirogon is a regular tessellation of the line, subdividing it into infinitely many equal segments. It has infinitely many vertices and edges. Its Schläfli symbol is {∞}, and Coxeter diagram Template:CDD.

...File:Regular apeirogon.svg...

It exists as the limit of the Template:Mvar-gon as Template:Mvar tends to infinity, as follows:

Name Monogon Digon Triangle Square Pentagon Hexagon Heptagon p-gon Apeirogon
Schläfli {1} {2} {3} {4} {5} {6} {7} {p} {∞}
Symmetry D1, [ ] D2, [2] D3, [3] D4, [4] D5, [5] D6, [6] D7, [7] [p]
Coxeter Template:CDD or Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD Template:CDD
Image File:Monogon.svg File:Digon.svg File:Regular triangle.svg File:Regular quadrilateral.svg File:Regular pentagon.svg File:Regular hexagon.svg File:Regular heptagon.svg File:Regular apeirogon.svg

Apeirogons in the hyperbolic plane, most notably the regular apeirogon, {∞}, can have a curvature just like finite polygons of the Euclidean plane, with the vertices circumscribed by horocycles or hypercycles rather than circles.

Regular apeirogons that are scaled to converge at infinity have the symbol {∞} and exist on horocycles, while more generally they can exist on hypercycles.

{∞} {iπ/λ}
File:Hyperbolic apeirogon example.png
Apeirogon on horocycle
File:Pseudogon example.png
Apeirogon on hypercycle

Above are two regular hyperbolic apeirogons in the Poincaré disk model, the right one shows perpendicular reflection lines of divergent fundamental domains, separated by length λ.

Skew apeirogonsEdit

A skew apeirogon in two dimensions forms a zig-zag line in the plane. If the zig-zag is even and symmetrical, then the apeirogon is regular.

Skew apeirogons can be constructed in any number of dimensions. In three dimensions, a regular skew apeirogon traces out a helical spiral and may be either left- or right-handed.

2 dimensions 3 dimensions
File:Regular zig-zag.svg
Zig-zag apeirogon
File:Triangular helix.png
Helix apeirogon

3-apeirotopes (apeirohedra)Edit

Euclidean tilingsEdit

There are six regular tessellations of the plane: the three listed below, and their corresponding Petrials.

Name Square tiling
(quadrille)
Triangular tiling
(deltille)
Hexagonal tiling
(hextille)
Symmetry p4m, [4,4], (*442) p6m, [6,3], (*632)
Schläfli {p,q} {4,4} {3,6} {6,3}
Coxeter diagram Template:CDD Template:CDD Template:CDD
Image File:Uniform tiling 44-t0.svg File:Uniform tiling 63-t2-red.svg File:Uniform tiling 63-t0.svg

There are two improper regular tilings: {∞,2}, an apeirogonal dihedron, made from two apeirogons, each filling half the plane; and secondly, its dual, {2,∞}, an apeirogonal hosohedron, seen as an infinite set of parallel lines.

File:Apeirogonal tiling.png
{∞,2}, Template:CDD
File:Apeirogonal hosohedron.png
{2,∞}, Template:CDD

Euclidean star-tilingsEdit

There are no regular plane tilings of star polygons. There are many enumerations that fit in the plane (1/p + 1/q = 1/2), like {8/3,8}, {10/3,5}, {5/2,10}, {12/5,12}, etc., but none repeat periodically.

Hyperbolic tilingsEdit

Tessellations of hyperbolic 2-space are hyperbolic tilings. There are infinitely many regular tilings in H2. As stated above, every positive integer pair {p,q} such that 1/p + 1/q < 1/2 gives a hyperbolic tiling. In fact, for the general Schwarz triangle (pqr) the same holds true for 1/p + 1/q + 1/r < 1.

There are a number of different ways to display the hyperbolic plane, including the Poincaré disk model which maps the plane into a circle, as shown below. It should be recognized that all of the polygon faces in the tilings below are equal-sized and only appear to get smaller near the edges due to the projection applied, very similar to the effect of a camera fisheye lens.

There are infinitely many flat regular 3-apeirotopes (apeirohedra) as regular tilings of the hyperbolic plane, of the form {p,q}, with p+q<pq/2.

  • {3,7}, {3,8}, {3,9} ... {3,∞}
  • {4,5}, {4,6}, {4,7} ... {4,∞}
  • {5,4}, {5,5}, {5,6} ... {5,∞}
  • {6,4}, {6,5}, {6,6} ... {6,∞}
  • {7,3}, {7,4}, {7,5} ... {7,∞}
  • {8,3}, {8,4}, {8,5} ... {8,∞}
  • {9,3}, {9,4}, {9,5} ... {9,∞}
  • ...
  • {∞,3}, {∞,4}, {∞,5} ... {∞,∞}

A sampling: Template:Regular hyperbolic tiling table

The tilings {p, ∞} have ideal vertices, on the edge of the Poincaré disk model. Their duals {∞, p} have ideal apeirogonal faces, meaning that they are inscribed in horocycles. One could go further (as is done in the table above) and find tilings with ultra-ideal vertices, outside the Poincaré disk, which are dual to tiles inscribed in hypercycles; in what is symbolised {p, iπ/λ} above, infinitely many tiles still fit around each ultra-ideal vertex.<ref name=hyphon>Roice Nelson and Henry Segerman, Visualizing Hyperbolic Honeycombs Template:Webarchive</ref> (Parallel lines in extended hyperbolic space meet at an ideal point; ultraparallel lines meet at an ultra-ideal point.)<ref>Irving Adler, A New Look at Geometry (2012 Dover edition), p.233</ref>

Hyperbolic star-tilingsEdit

There are 2 infinite forms of hyperbolic tilings whose faces or vertex figures are star polygons: {m/2, m} and their duals {m, m/2} with m = 7, 9, 11, ....Template:Sfnp The {m/2, m} tilings are stellations of the {m, 3} tilings while the {m, m/2} dual tilings are facetings of the {3, m} tilings and greateningsTemplate:Efn of the {m, 3} tilings.

The patterns {m/2, m} and {m, m/2} continue for odd m < 7 as polyhedra: when m = 5, we obtain the small stellated dodecahedron and great dodecahedron,Template:Sfnp and when m = 3, the case degenerates to a tetrahedron. The other two Kepler–Poinsot polyhedra (the great stellated dodecahedron and great icosahedron) do not have regular hyperbolic tiling analogues. If m is even, depending on how we choose to define {m/2}, we can either obtain degenerate double covers of other tilings or compound tilings.

Name Schläfli Coxeter diagram Image Face type
{p}
Vertex figure
{q}
Density Symmetry Dual
Order-7 heptagrammic tiling {7/2,7} Template:CDD File:Hyperbolic tiling 7-2 7.png {7/2}
File:Star polygon 7-2.svg
{7}
File:Regular heptagon.svg
3 *732
[7,3]
Heptagrammic-order heptagonal tiling
Heptagrammic-order heptagonal tiling {7,7/2} Template:CDD File:Hyperbolic tiling 7 7-2.png {7}
File:Regular heptagon.svg
{7/2}
File:Star polygon 7-2.svg
3 *732
[7,3]
Order-7 heptagrammic tiling
Order-9 enneagrammic tiling {9/2,9} Template:CDD File:Hyperbolic tiling 9-2 9.png {9/2}
File:Star polygon 9-2.svg
{9}
File:Regular nonagon.svg
3 *932
[9,3]
Enneagrammic-order enneagonal tiling
Enneagrammic-order enneagonal tiling {9,9/2} Template:CDD File:Hyperbolic tiling 9 9-2.png {9}
File:Regular nonagon.svg
{9/2}
File:Star polygon 9-2.svg
3 *932
[9,3]
Order-9 enneagrammic tiling
Order-11 hendecagrammic tiling {11/2,11} Template:CDD File:Order-11 hendecagrammic tiling.png {11/2}
File:Star polygon 11-2.svg
{11}
File:Regular hendecagon.svg
3 *11.3.2
[11,3]
Hendecagrammic-order hendecagonal tiling
Hendecagrammic-order hendecagonal tiling {11,11/2} Template:CDD File:Hendecagrammic-order hendecagonal tiling.png {11}
File:Regular hendecagon.svg
{11/2}
File:Star polygon 11-2.svg
3 *11.3.2
[11,3]
Order-11 hendecagrammic tiling
Order-p p-grammic tiling {p/2,p} Template:CDD   {p/2} {p} 3 *p32
[p,3]
p-grammic-order p-gonal tiling
p-grammic-order p-gonal tiling {p,p/2} Template:CDD   {p} {p/2} 3 *p32
[p,3]
Order-p p-grammic tiling

Skew apeirohedra in Euclidean 3-spaceEdit

Template:Expand section There are three regular skew apeirohedra in Euclidean 3-space, with planar faces.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite book</ref> They share the same vertex arrangement and edge arrangement of 3 convex uniform honeycombs.

  • 6 squares around each vertex: {4,6|4}
  • 4 hexagons around each vertex: {6,4|4}
  • 6 hexagons around each vertex: {6,6|3}
File:Pure 3-dimensional apeirohedra chart.png
12 3-dimensional "pure" apeirohedra based on the structure of the cubic honeycomb, {4,3,4}.Template:Sfnp A π petrie dual operator replaces faces with petrie polygons; δ is a dual operator reverses vertices and faces; φk is a kth facetting operator; η is a halving operator, and σ skewing halving operator.
Regular skew polyhedra with planar faces
File:Mucube external.png
{4,6|4}
File:Muoctahedron external.png
{6,4|4}
File:Mutetrahedron external.png
{6,6|3}

Allowing for skew faces, there are 30 regular apeirohedra in Euclidean 3-space.Template:Sfnp These include the 12 blended apeirohedra created by blends with the Euclidean planar apeirohedra, and 18 pure apeirohedra, which cannot be expressed as a non-trivial blend including the planar apeirohedra and the three 3-dimensional apeirohedra above.

The 3-dimensional pure apeirohedra are:

Skew apeirohedra in hyperbolic 3-spaceEdit

There are 31 regular skew apeirohedra with convex faces in hyperbolic 3-space with compact or paracompact symmetry:<ref>Template:Cite journal Note: His paper says there are 32, but one is self-dual, leaving 31.</ref>

  • 14 are compact: {8,10|3}, {10,8|3}, {10,4|3}, {4,10|3}, {6,4|5}, {4,6|5}, {10,6|3}, {6,10|3}, {8,8|3}, {6,6|4}, {10,10|3},{6,6|5}, {8,6|3}, and {6,8|3}.
  • 17 are paracompact: {12,10|3}, {10,12|3}, {12,4|3}, {4,12|3}, {6,4|6}, {4,6|6}, {8,4|4}, {4,8|4}, {12,6|3}, {6,12|3}, {12,12|3}, {6,6|6}, {8,6|4}, {6,8|4}, {12,8|3}, {8,12|3}, and {8,8|4}.

4-apeirotopesEdit

Tessellations of Euclidean 3-spaceEdit

File:Cubic honeycomb.png
Edge framework of cubic honeycomb, {4,3,4}

There is only one non-degenerate regular tessellation of 3-space (honeycombs), {4, 3, 4}:Template:Sfnp

Name Schläfli
{p,q,r}
Coxeter
Template:CDD
Cell
type
{p,q}
Face
type
{p}
Edge
figure
{r}
Vertex
figure

{q,r}
χ Dual
Cubic honeycomb {4,3,4} Template:CDD {4,3} {4} {4} {3,4} 0 Self-dual

Improper tessellations of Euclidean 3-spaceEdit

File:Order-4 square hosohedral honeycomb-sphere.png
Regular {2,4,4} honeycomb, seen projected into a sphere.

There are six improper regular tessellations, pairs based on the three regular Euclidean tilings. Their cells and vertex figures are all regular hosohedra {2,n}, dihedra, {n,2}, and Euclidean tilings. These improper regular tilings are constructionally related to prismatic uniform honeycombs by truncation operations. They are higher-dimensional analogues of the order-2 apeirogonal tiling and apeirogonal hosohedron.

Schläfli
{p,q,r}
Coxeter
diagram
Cell
type
{p,q}
Face
type
{p}
Edge
figure
{r}
Vertex
figure

{q,r}
{2,4,4} Template:CDD {2,4} {2} {4} {4,4}
{2,3,6} Template:CDD {2,3} {2} {6} {3,6}
{2,6,3} Template:CDD {2,6} {2} {3} {6,3}
{4,4,2} Template:CDD {4,4} {4} {2} {4,2}
{3,6,2} Template:CDD {3,6} {3} {2} {6,2}
{6,3,2} Template:CDD {6,3} {6} {2} {3,2}

Tessellations of hyperbolic 3-spaceEdit

There are 15 flat regular honeycombs of hyperbolic 3-space:

  • 4 are compact: {3,5,3}, {4,3,5}, {5,3,4}, and {5,3,5}
  • while 11 are paracompact: {3,3,6}, {6,3,3}, {3,4,4}, {4,4,3}, {3,6,3}, {4,3,6}, {6,3,4}, {4,4,4}, {5,3,6}, {6,3,5}, and {6,3,6}.
4 compact regular honeycombs
File:H3 534 CC center.png
{5,3,4}
File:H3 535 CC center.png
{5,3,5}
File:H3 435 CC center.png
{4,3,5}
File:H3 353 CC center.png
{3,5,3}
4 of 11 paracompact regular honeycombs
File:H3 344 CC center.png
{3,4,4}
File:H3 363 FC boundary.png
{3,6,3}
File:H3 443 FC boundary.png
{4,4,3}
File:H3 444 FC boundary.png
{4,4,4}

Tessellations of hyperbolic 3-space can be called hyperbolic honeycombs. There are 15 hyperbolic honeycombs in H3, 4 compact and 11 paracompact.

4 compact regular honeycombs
Name Schläfli
Symbol
{p,q,r}
Coxeter
Template:CDD
Cell
type
{p,q}
Face
type
{p}
Edge
figure
{r}
Vertex
figure

{q,r}
χ Dual
Icosahedral honeycomb {3,5,3} Template:CDD {3,5} {3} {3} {5,3} 0 Self-dual
Order-5 cubic honeycomb {4,3,5} Template:CDD {4,3} {4} {5} {3,5} 0 {5,3,4}
Order-4 dodecahedral honeycomb {5,3,4} Template:CDD {5,3} {5} {4} {3,4} 0 {4,3,5}
Order-5 dodecahedral honeycomb {5,3,5} Template:CDD {5,3} {5} {5} {3,5} 0 Self-dual

There are also 11 paracompact H3 honeycombs (those with infinite (Euclidean) cells and/or vertex figures): {3,3,6}, {6,3,3}, {3,4,4}, {4,4,3}, {3,6,3}, {4,3,6}, {6,3,4}, {4,4,4}, {5,3,6}, {6,3,5}, and {6,3,6}.

11 paracompact regular honeycombs
Name Schläfli
Symbol
{p,q,r}
Coxeter
Template:CDD
Cell
type
{p,q}
Face
type
{p}
Edge
figure
{r}
Vertex
figure

{q,r}
χ Dual
Order-6 tetrahedral honeycomb {3,3,6} Template:CDD {3,3} {3} {6} {3,6} 0 {6,3,3}
Hexagonal tiling honeycomb {6,3,3} Template:CDD {6,3} {6} {3} {3,3} 0 {3,3,6}
Order-4 octahedral honeycomb {3,4,4} Template:CDD {3,4} {3} {4} {4,4} 0 {4,4,3}
Square tiling honeycomb {4,4,3} Template:CDD {4,4} {4} {3} {4,3} 0 {3,3,4}
Triangular tiling honeycomb {3,6,3} Template:CDD {3,6} {3} {3} {6,3} 0 Self-dual
Order-6 cubic honeycomb {4,3,6} Template:CDD {4,3} {4} {4} {3,6} 0 {6,3,4}
Order-4 hexagonal tiling honeycomb {6,3,4} Template:CDD {6,3} {6} {4} {3,4} 0 {4,3,6}
Order-4 square tiling honeycomb {4,4,4} Template:CDD {4,4} {4} {4} {4,4} 0 Self-dual
Order-6 dodecahedral honeycomb {5,3,6} Template:CDD {5,3} {5} {5} {3,6} 0 {6,3,5}
Order-5 hexagonal tiling honeycomb {6,3,5} Template:CDD {6,3} {6} {5} {3,5} 0 {5,3,6}
Order-6 hexagonal tiling honeycomb {6,3,6} Template:CDD {6,3} {6} {6} {3,6} 0 Self-dual

Noncompact solutions exist as Lorentzian Coxeter groups, and can be visualized with open domains in hyperbolic space (the fundamental tetrahedron having ultra-ideal vertices). All honeycombs with hyperbolic cells or vertex figures and do not have 2 in their Schläfli symbol are noncompact. Template:Regular honeycomb table

There are no regular hyperbolic star-honeycombs in H3: all forms with a regular star polyhedron as cell, vertex figure or both end up being spherical.

Ideal vertices now appear when the vertex figure is a Euclidean tiling, becoming inscribable in a horosphere rather than a sphere. They are dual to ideal cells (Euclidean tilings rather than finite polyhedra). As the last number in the Schläfli symbol rises further, the vertex figure becomes hyperbolic, and vertices become ultra-ideal (so the edges do not meet within hyperbolic space). In honeycombs {p, q, ∞} the edges intersect the Poincaré ball only in one ideal point; the rest of the edge has become ultra-ideal. Continuing further would lead to edges that are completely ultra-ideal, both for the honeycomb and for the fundamental simplex (though still infinitely many {p, q} would meet at such edges). In general, when the last number of the Schläfli symbol becomes ∞, faces of codimension two intersect the Poincaré hyperball only in one ideal point.<ref name=hyphon/>

5-apeirotopesEdit

Tessellations of Euclidean 4-spaceEdit

There are three kinds of infinite regular tessellations (honeycombs) that can tessellate Euclidean four-dimensional space:

3 regular Euclidean honeycombs
Name Schläfli
Symbol
{p,q,r,s}
Facet
type
{p,q,r}
Cell
type
{p,q}
Face
type
{p}
Face
figure
{s}
Edge
figure
{r,s}
Vertex
figure

{q,r,s}
Dual
Tesseractic honeycomb {4,3,3,4} {4,3,3} {4,3} {4} {4} {3,4} {3,3,4} Self-dual
16-cell honeycomb {3,3,4,3} {3,3,4} {3,3} {3} {3} {4,3} {3,4,3} {3,4,3,3}
24-cell honeycomb {3,4,3,3} {3,4,3} {3,4} {3} {3} {3,3} {4,3,3} {3,3,4,3}
File:Tesseractic tetracomb.png
Projected portion of {4,3,3,4}
(Tesseractic honeycomb)
File:Demitesseractic tetra hc.png
Projected portion of {3,3,4,3}
(16-cell honeycomb)
File:Icositetrachoronic tetracomb.png
Projected portion of {3,4,3,3}
(24-cell honeycomb)

There are also the two improper cases {4,3,4,2} and {2,4,3,4}.

There are three flat regular honeycombs of Euclidean 4-space:Template:Sfnp

  • {4,3,3,4}, {3,3,4,3}, and {3,4,3,3}.

There are seven flat regular convex honeycombs of hyperbolic 4-space:Template:Sfnp

  • 5 are compact: {3,3,3,5}, {5,3,3,3}, {4,3,3,5}, {5,3,3,4}, {5,3,3,5}
  • 2 are paracompact: {3,4,3,4}, and {4,3,4,3}.

There are four flat regular star honeycombs of hyperbolic 4-space:Template:Sfnp

  • {5/2,5,3,3}, {3,3,5,5/2}, {3,5,5/2,5}, and {5,5/2,5,3}.

Tessellations of hyperbolic 4-spaceEdit

There are seven convex regular honeycombs and four star-honeycombs in H4 space.Template:Sfnp Five convex ones are compact, and two are paracompact.

Five compact regular honeycombs in H4:

5 compact regular honeycombs
Name Schläfli
Symbol
{p,q,r,s}
Facet
type
{p,q,r}
Cell
type
{p,q}
Face
type
{p}
Face
figure
{s}
Edge
figure
{r,s}
Vertex
figure

{q,r,s}
Dual
Order-5 5-cell honeycomb {3,3,3,5} {3,3,3} {3,3} {3} {5} {3,5} {3,3,5} {5,3,3,3}
120-cell honeycomb {5,3,3,3} {5,3,3} {5,3} {5} {3} {3,3} {3,3,3} {3,3,3,5}
Order-5 tesseractic honeycomb {4,3,3,5} {4,3,3} {4,3} {4} {5} {3,5} {3,3,5} {5,3,3,4}
Order-4 120-cell honeycomb {5,3,3,4} {5,3,3} {5,3} {5} {4} {3,4} {3,3,4} {4,3,3,5}
Order-5 120-cell honeycomb {5,3,3,5} {5,3,3} {5,3} {5} {5} {3,5} {3,3,5} Self-dual

The two paracompact regular H4 honeycombs are: {3,4,3,4}, {4,3,4,3}.

2 paracompact regular honeycombs
Name Schläfli
Symbol
{p,q,r,s}
Facet
type
{p,q,r}
Cell
type
{p,q}
Face
type
{p}
Face
figure
{s}
Edge
figure
{r,s}
Vertex
figure

{q,r,s}
Dual
Order-4 24-cell honeycomb {3,4,3,4} {3,4,3} {3,4} {3} {4} {3,4} {4,3,4} {4,3,4,3}
Cubic honeycomb honeycomb {4,3,4,3} {4,3,4} {4,3} {4} {3} {4,3} {3,4,3} {3,4,3,4}

Noncompact solutions exist as Lorentzian Coxeter groups, and can be visualized with open domains in hyperbolic space (the fundamental 5-cell having some parts inaccessible beyond infinity). All honeycombs which are not shown in the set of tables below and do not have 2 in their Schläfli symbol are noncompact. Template:Regular tetracomb table

Star tessellations of hyperbolic 4-spaceEdit

There are four regular star-honeycombs in H4 space, all compact:

4 compact regular star-honeycombs
Name Schläfli
Symbol
{p,q,r,s}
Facet
type
{p,q,r}
Cell
type
{p,q}
Face
type
{p}
Face
figure
{s}
Edge
figure
{r,s}
Vertex
figure

{q,r,s}
Dual Density
Small stellated 120-cell honeycomb {5/2,5,3,3} {5/2,5,3} {5/2,5} {5/2} {3} {3,3} {5,3,3} {3,3,5,5/2} 5
Pentagrammic-order 600-cell honeycomb {3,3,5,5/2} {3,3,5} {3,3} {3} {5/2} {5,5/2} {3,5,5/2} {5/2,5,3,3} 5
Order-5 icosahedral 120-cell honeycomb {3,5,5/2,5} {3,5,5/2} {3,5} {3} {5} {5/2,5} {5,5/2,5} {5,5/2,5,3} 10
Great 120-cell honeycomb {5,5/2,5,3} {5,5/2,5} {5,5/2} {5} {3} {5,3} {5/2,5,3} {3,5,5/2,5} 10

6-apeirotopesEdit

There is only one flat regular honeycomb of Euclidean 5-space: (previously listed above as tessellations)Template:Sfnp

  • {4,3,3,3,4}

There are five flat regular regular honeycombs of hyperbolic 5-space, all paracompact: (previously listed above as tessellations)Template:Sfnp

  • {3,3,3,4,3}, {3,4,3,3,3}, {3,3,4,3,3}, {3,4,3,3,4}, and {4,3,3,4,3}

Tessellations of Euclidean 5-spaceEdit

The hypercubic honeycomb is the only family of regular honeycombs that can tessellate each dimension, five or higher, formed by hypercube facets, four around every ridge.

Name Schläfli
{p1, p2, ..., pn−1}
Facet
type
Vertex
figure
Dual
Square tiling {4,4} {4} {4} Self-dual
Cubic honeycomb {4,3,4} {4,3} {3,4} Self-dual
Tesseractic honeycomb {4,32,4} {4,32} {32,4} Self-dual
5-cube honeycomb {4,33,4} {4,33} {33,4} Self-dual
6-cube honeycomb {4,34,4} {4,34} {34,4} Self-dual
7-cube honeycomb {4,35,4} {4,35} {35,4} Self-dual
8-cube honeycomb {4,36,4} {4,36} {36,4} Self-dual
n-hypercubic honeycomb {4,3n−2,4} {4,3n−2} {3n−2,4} Self-dual

In E5, there are also the improper cases {4,3,3,4,2}, {2,4,3,3,4}, {3,3,4,3,2}, {2,3,3,4,3}, {3,4,3,3,2}, and {2,3,4,3,3}. In En, {4,3n−3,4,2} and {2,4,3n−3,4} are always improper Euclidean tessellations.

Tessellations of hyperbolic 5-spaceEdit

There are 5 regular honeycombs in H5, all paracompact, which include infinite (Euclidean) facets or vertex figures: {3,4,3,3,3}, {3,3,4,3,3}, {3,3,3,4,3}, {3,4,3,3,4}, and {4,3,3,4,3}.

There are no compact regular tessellations of hyperbolic space of dimension 5 or higher and no paracompact regular tessellations in hyperbolic space of dimension 6 or higher.

5 paracompact regular honeycombs
Name Schläfli
Symbol
{p,q,r,s,t}
Facet
type
{p,q,r,s}
4-face
type
{p,q,r}
Cell
type
{p,q}
Face
type
{p}
Cell
figure
{t}
Face
figure
{s,t}
Edge
figure
{r,s,t}
Vertex
figure

{q,r,s,t}
Dual
5-orthoplex honeycomb {3,3,3,4,3} {3,3,3,4} {3,3,3} {3,3} {3} {3} {4,3} {3,4,3} {3,3,4,3} {3,4,3,3,3}
24-cell honeycomb honeycomb {3,4,3,3,3} {3,4,3,3} {3,4,3} {3,4} {3} {3} {3,3} {3,3,3} {4,3,3,3} {3,3,3,4,3}
16-cell honeycomb honeycomb {3,3,4,3,3} {3,3,4,3} {3,3,4} {3,3} {3} {3} {3,3} {4,3,3} {3,4,3,3} self-dual
Order-4 24-cell honeycomb honeycomb {3,4,3,3,4} {3,4,3,3} {3,4,3} {3,4} {3} {4} {3,4} {3,3,4} {4,3,3,4} {4,3,3,4,3}
Tesseractic honeycomb honeycomb {4,3,3,4,3} {4,3,3,4} {4,3,3} {4,3} {4} {3} {4,3} {3,4,3} {3,3,4,3} {3,4,3,3,4}

Since there are no regular star n-polytopes for n ≥ 5, that could be potential cells or vertex figures, there are no more hyperbolic star honeycombs in Hn for n ≥ 5.

Apeirotopes of rank 7 or moreEdit

Tessellations of hyperbolic 6-space and higherEdit

There are no regular compact or paracompact tessellations of hyperbolic space of dimension 6 or higher. However, any Schläfli symbol of the form {p,q,r,s,...} not covered above (p,q,r,s,... natural numbers above 2, or infinity) will form a noncompact tessellation of hyperbolic n-space.<ref name=hyphon/>

Abstract polytopesEdit

The abstract polytopes arose out of an attempt to study polytopes apart from the geometrical space they are embedded in. They include the tessellations of spherical, Euclidean and hyperbolic space, and of other manifolds. There are infinitely many of every rank greater than 1. See this atlas for a sample. Some notable examples of abstract regular polytopes that do not appear elsewhere in this list are the 11-cell, {3,5,3}, and the 57-cell, {5,3,5}, which have regular projective polyhedra as cells and vertex figures.

The elements of an abstract polyhedron are its body (the maximal element), its faces, edges, vertices and the null polytope or empty set. These abstract elements can be mapped into ordinary space or realised as geometrical figures. Some abstract polyhedra have well-formed or faithful realisations, others do not. A flag is a connected set of elements of each rank - for a polyhedron that is the body, a face, an edge of the face, a vertex of the edge, and the null polytope. An abstract polytope is said to be regular if its combinatorial symmetries are transitive on its flags - that is to say, that any flag can be mapped onto any other under a symmetry of the polyhedron. Abstract regular polytopes remain an active area of research.

Five such regular abstract polyhedra, which can not be realised faithfully and symmetrically, were identified by H. S. M. Coxeter in his book Regular Polytopes (1977) and again by J. M. Wills in his paper "The combinatorially regular polyhedra of index 2" (1987).<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> They are all topologically equivalent to toroids. Their construction, by arranging n faces around each vertex, can be repeated indefinitely as tilings of the hyperbolic plane. In the diagrams below, the hyperbolic tiling images have colors corresponding to those of the polyhedra images.

Polyhedron File:DU36 medial rhombic triacontahedron.png
Medial rhombic triacontahedron
File:Dodecadodecahedron.png
Dodecadodecahedron
File:DU41 medial triambic icosahedron.png
Medial triambic icosahedron
File:Ditrigonal dodecadodecahedron.png
Ditrigonal dodecadodecahedron
File:Excavated dodecahedron.png
Excavated dodecahedron
Vertex figure {5}, {5/2}
File:Regular polygon 5.svgFile:Pentagram green.svg
(5.5/2)2
File:Dodecadodecahedron vertfig.png
{5}, {5/2}
File:Regular polygon 5.svgFile:Pentagram green.svg
(5.5/3)3
File:Ditrigonal dodecadodecahedron vertfig.png
File:Medial triambic icosahedron face.svg
Faces 30 rhombi
File:Rhombus definition2.svg
12 pentagons
12 pentagrams
File:Regular polygon 5.svgFile:Pentagram green.svg
20 hexagons
File:Medial triambic icosahedron face.svg
12 pentagons
12 pentagrams
File:Regular polygon 5.svgFile:Pentagram green.svg
20 hexagrams
File:Star hexagon face.png
Tiling File:Uniform tiling 45-t0.png
{4, 5}
File:Uniform tiling 552-t1.png
{5, 4}
File:Uniform tiling 65-t0.png
{6, 5}
File:Uniform tiling 553-t1.png
{5, 6}
File:Uniform tiling 66-t2.png
{6, 6}
χ −6 −6 −16 −16 −20

These occur as dual pairs as follows:

See alsoEdit

NotesEdit

Template:Notelist-lr

SubnotesEdit

Template:Reflist

ReferencesEdit

Template:Reflist

CitationsEdit

Template:Refbegin

Template:Refend

External linksEdit

Template:Polytopes Template:Honeycombs Template:Tessellation