fact: Record plane_embedding (G : sgraph) := { emb_map : hypermap; emb_fun :> emb_map -> G; emb_embedding : embedding emb_fun; emb_planar : planar emb_map }.
imports: mathcomp(all_ssreflect) fourcolor(hypermap geometry color coloring walkup combinatorial4ct cfmap) GraphTheory(edone preliminaries bij digraph sgraph) GraphTheory(connectivity minor hmap_ops smerge hcycle arc)