#
|
Face
|
Group
|
0
|
|
D4
|
1
|
|
D4
|
2
|
|
D2d
|
3
|
|
D2d
|
4
|
|
D4
|
5
|
|
D4
|
6
|
|
D2x
|
7
|
|
D2x
|
8
|
|
D4
|
9
|
|
D4
|
The die faces' symmetry groups are the symmetry
group of the square and two of its subgroups.
They are all rotation-reflection (dihedral) groups.
Group
|
Elements
|
D2x
|
Rotations: 0°, 180°
|
Reflections: axial: horizontal and vertical
|
D2d
|
Rotations: 0°, 180°
|
Reflections: diagonal: both diagonals
|
D4
|
Rotations: 0°, 90°, 180°, 270°
|
Reflections: both axes and both diagonals
|
The die itself, ignoring face markers,
has octahedral symmetry, Oh.
Faces on a Die: Their Placement
Opposite faces usually add up to 7,
but within this constraint,
there are 24 = 16 possible arrangements:
-
2: Reflection of the die
-
2: Rotation of face 2 by 90°
-
2: Rotation of face 3 by 90°
-
2: Rotation of face 6 by 90°
Non-Cubical Dice
The most common kind is the coin.
Flipping a coin is eseentially using it as a d2 die.
Players of tabletop role-playing games have used
numerous kinds of dice, distinguished by them
as d<number>. They include:
Family
|
Number of Sides
|
Platonic solids
|
4, 6, 8, 12, 20
|
Catalan solids
|
12, 24, 30, 48, 60, 120
|
Bipyramids
|
Even numbers ≥ 6
|
Trapezohedra
|
Even numbers ≥ 6
|
Prisms
|
Integers ≥ 3
|
Antiprisms
|
Even numbers ≥ 2
|
Degeneracies:
-
2-antiprism: tetrahedron
-
3-antiprism: octahedron
-
3-trapezohedron, 4-prism: cube
To my symmetry index page