The map on the rectangle is colored in a straightforward manner. The color scheme from the rectangle is retained as much as possible when coloring on the torus. Remember that on the torus regions at the left and right ends are glued together and thus need different colors (as in the introduction of blue in the second row below). Also on the torus, regions at the top and bottom of the rectangle are glued together and thus need different colors (as in the introduction of yellow in the second row below).
Map on the rectangle | Map on the torus |