proposition: Lemma planar_embr : planar Gr.
proof: Proof. by have:= planarGm; rewrite /planar (genus_patch ppGm) addn_eq0 => /andP[]. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap geometry color chromogram coloring patch) fourcolor(snip revsnip kempe birkhoff contract)