proposition: Lemma scycle_snipd_ring : sfcycle edge snipd_ring.
proof: Proof. by rewrite /scycle simple_snipd_ring andbT; case/andP: ucycle_snipd_ring. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap jordan color geometry patch)