proposition: Lemma end1g_edge p : end1g (gedge p) = end0g p.
proof: Proof. by rewrite -end0g_edge gedge2. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(div choice order ssralg ssrnum ssrint intdiv) fourcolor(hypermap)