Square grid on a torus
Translation generators
Generator
x
y
A
B
Canonical form
Generator
x
y
A
B
R
0
0
0
0
U
0
0
0
0
Generator
R
U
A
0
0
B
0
0
Unit cell
Number of positions:
.
Infinite grid of cells
x
y
content
color
rotation
mirror