Space Groups
The space groups in 2-D are called Wallpaper Groups. In 3-D, the space groups are the symmetry Groupspossible in a crystal lattice with the translation symmetry element. There are 230 space groups in 
, although 11are Mirror Images of each other. They are listed by Hermann-Mauguin Symbol in Cotton (1990).
References
Arfken, G. ``Crystallographic Point and Space Groups.'' Mathematical Methods for Physicists, 3rd ed. Orlando, FL: Academic Press, p. 248-249, 1985. Buerger, M. J. Elementary Crystallography. New York: Wiley, 1956. Cotton, F. A. Chemical Applications of Group Theory, 3rd ed. New York: Wiley, pp. 250-251, 1990.
- Rubik's Cube
- Rudin-Shapiro Sequence
- Rudvalis Group
- Rule
- Ruled Surface
- Rule of 72
- Ruler
- Ruler Function
- Ruling
- Run
- Runge-Kutta Method
- Runge-Walsh Theorem
- Running Knot
- Russell's Antinomy
- Russell's Paradox
- Russian Multiplication
- Russian Roulette
- Ryser Formula
- Rényi's Parking Constants
- Rössler Model
- Saalschützian
- Saalschütz's Theorem
- s-Additive Sequence
- Saddle
- Saddle-Node Bifurcation