OFFSET
0,1
COMMENTS
r,l,u,d,f,b are respectively right, left, up, down, front, back faces of a 3 X 3 X 3 Rubik's Cube. Set M=2, R=3, L=5, U=7, D=11, F=13, B=17, where M is a 90-degree turn of the middle slice of Rubik's Cube; R is a 90-degree turn of the right face, L is a 90-degree turn of the left face... The moves to permute (ufl,ubr)(ufr,ubl) corners are (M^2*U)*(M^2*U^2)*(M^2*U)*(M^2*U^2) = (2^2*7)*(2^2*7^2)*(2^2*7)*(2^2*7^2) = 28*196*28*196. Note that as the order of a 90-degree turn T is 4, then T^2 = T^-2 and T^3 = T^-1. Moves adapted from 'Adventures in group theory', D. Joyner, J. Hopkins Press.
EXAMPLE
28 = 2^2*7 codes M^2*U moves.
CROSSREFS
KEYWORD
fini,full,nonn
AUTHOR
Giorgio Balzarotti & Paolo P. Lava, Nov 29 2007
STATUS
approved