 Then the Hajós construction forms a new graph that combines the two graphs by identifying vertices and into a single vertex, removing the two edges and , and adding a new edge .For example, let and each be a complete graph on four vertices; because of the symmetry of these graphs, the choice of which edge to select from each of them is unimportant.In this case, the result of applying the Hajós construction is the Moser spindle, a seven-vertex unit distance graph that requires four colors.