English: The lines are the reflecting hyperplanes of the affine symmetric group of type A_2. They divide the plane into alcoves; the fundamental alcove is shaded, and its bounding lines (corresponding to the Coxeter generators) are thick. Each alcove A is labeled by the affine permutation that sends A to the fundamental alcove. Inverse labeling to File:Alcoves_labeled_by_affine_permutations.png