fact: Definition add_node_node (z : ecp_dart G) : ecp_dart G := match z with | IcpX => Icp (node x) | IcpXe => IcpXe | Icp z => if z == x then IcpX else Icp (node z) end.
imports: mathcomp(all_ssreflect) GraphTheory(edone preliminaries bij) fourcolor(hypermap geometry cfmap jordan color coloring combinatorial4ct) fourcolor(walkup)