A regular octahedron has 24 rotational (or orientation-preserving) symmetries, and a symmetry order of 48 including transformations that combine a reflection and a rotation. A cube has the same set of symmetries, since it is the dual of an octahedron.
The group of orientation-preserving symmetries is S4, the symmetric group or the group of permutations of four objects, since there is exactly one such symmetry for each permutation of the four pairs of opposite sides of the octahedron.
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Chiral and full (or achiral) octahedral symmetry are the discrete point symmetries (or equivalently, symmetries on the sphere) with the largest symmetry groups compatible with translational symmetry. They are among the crystallographic point groups of the cubic crystal system.
O, 432, or [4,3]+ of order 24, is chiral octahedral symmetry or rotational octahedral symmetry . This group is like chiral tetrahedral symmetry T, but the C2 axes are now C4 axes, and additionally there are 6 C2 axes, through the midpoints of the edges of the cube. Td and O are isomorphic as abstract groups: they both correspond to S4, the symmetric group on 4 objects. Td is the union of T and the set obtained by combining each element of O \ T with inversion. O is the rotation group of the cube and the regular octahedron.
With the 4-fold axes as coordinate axes, a fundamental domain of Oh is given by 0 ≤ x ≤ y ≤ z. An object with this symmetry is characterized by the part of the object in the fundamental domain, for example the cube is given by z = 1, and the octahedron by x + y + z = 1 (or the corresponding inequalities, to get the solid instead of the surface). ax + by + cz = 1 gives a polyhedron with 48 faces, e.g. the disdyakis dodecahedron.
Faces are 8-by-8 combined to larger faces for a = b = 0 (cube) and 6-by-6 for a = b = c (octahedron).
(To be integrated in the rest of the text.)
The cube has 48 isometries, forming the symmetry group Oh, isomorphic to S4 × C2. They can be categorized as follows:
An isometry of the cube can be identified in various ways:
For cubes with colors or markings (like dice have), the symmetry group is a subgroup of Oh. Examples:
For some larger subgroups a cube with that group as symmetry group is not possible with just coloring whole faces. One has to draw some pattern on the faces. Examples:
The full symmetry of the cube (Oh) is preserved if and only if all faces have the same pattern such that the full symmetry of the square is preserved, with for the square a symmetry group of order 8.
The full symmetry of the cube under proper rotations (O) is preserved if and only if all faces have the same pattern with 4-fold rotational symmetry.
In Riemann surface theory, the Bolza surface, sometimes called the Bolza curve, is obtained as the ramified double cover of the Riemann sphere, with ramification locus at the set of vertices of the regular inscribed octahedron. Its automorphism group includes the hyperelliptic involution which flips the two sheets of the cover. The quotient by the order 2 subgroup generated by the hyperelliptic involution yields precisely the group of symmetries of the octahedron. Among the many remarkable properties of the Bolza surface is the fact that it maximizes the systole among all genus 2 hyperbolic surfaces.
Name | picture | Faces | Edges | Vertices | Vertex configuration | |
---|---|---|---|---|---|---|
snub cube or snub cuboctahedron (2 chiral forms) |
(Video) (Video) |
38 | 32 triangles 6 squares |
60 | 24 | 3,3,3,3,4 |
Name | picture | Dual Archimedean solid | Faces | Edges | Vertices | Face Polygon |
---|---|---|---|---|---|---|
pentagonal icositetrahedron | (Video)(Video) |
snub cube | 24 | 60 | 38 | irregular pentagon |
Name | Picture | Faces | Edges | Vertices | Edges per face | Faces meeting at each vertex |
---|---|---|---|---|---|---|
cube (hexahedron) | (Animation) |
6 | 12 | 8 | 4 | 3 |
octahedron | (Animation) |
8 | 12 | 6 | 3 | 4 |
(semi-regular: vertex-uniform)
Name | picture | Faces | Edges | Vertices | Vertex configuration | |
---|---|---|---|---|---|---|
cuboctahedron (quasi-regular: vertex- and edge-uniform) |
(Video) |
14 | 8 triangles 6 squares |
24 | 12 | 3,4,3,4 |
truncated cube or truncated hexahedron |
(Video) |
14 | 8 triangles 6 octagons |
36 | 24 | 3,8,8 |
truncated octahedron | (Video) |
14 | 6 squares 8 hexagons |
36 | 24 | 4,6,6 |
rhombicuboctahedron or small rhombicuboctahedron |
(Video) |
26 | 8 triangles 18 squares |
48 | 24 | 3,4,4,4 |
truncated cuboctahedron or great rhombicuboctahedron |
(Video) |
26 | 12 squares 8 hexagons 6 octagons |
72 | 48 | 4,6,8 |
(semi-regular duals: face-uniform)
Name | picture | Dual Archimedean solid | Faces | Edges | Vertices | Face polygon |
---|---|---|---|---|---|---|
rhombic dodecahedron (quasi-regular dual: face- and edge-uniform) |
(Video) |
cuboctahedron | 12 | 24 | 14 | rhombus |
triakis octahedron | (Video) |
truncated cube | 24 | 36 | 14 | isosceles triangle |
tetrakis hexahedron | (Video) |
truncated octahedron | 24 | 36 | 14 | isosceles triangle |
deltoidal icositetrahedron | (Video) |
rhombicuboctahedron | 24 | 48 | 26 | kite |
disdyakis dodecahedron or hexakis octahedron |
(Video) |
truncated cuboctahedron | 48 | 72 | 26 | scalene triangle |