fact: Record embedding (G : sgraph) (D : hypermap) (f : D -> G) := Embedding { emb_plain : plain D; emb_surj x : x \in codom f; emb_vertex d1 d2 : cnode d1 d2 = (f d1 == f d2); emb_edge d1 d2 : adjn d1 d2 = f d1 -- f d2 }.
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)