 If "H" is a connected graph, each vertex of "H" must have the same number of pre-images in "C"; this number is called the "ply" of the map, and "C" is called a covering graph of "G".If "C" and "H" are both finite, and "C" is a planar graph, then "C" is called a planar cover of "H".The graph of the dodecahedron has a symmetry that maps each vertex to the antipodal vertex.