From Graph Theory by Bondy, Murty
Image from wikipedia
I don't see how the picture holds according to the definition from the Graph Theory book.
Specifically, the definition says to assign the colors to the vertices of the sub triangles so that each color is missing from one side of the triangle but appears on the other two sides. However, in the picture, I see triangles with red on all sides.
Are we only considering that the definition hold for $T$ only? That is, the outside edges only?