proposition: Lemma add_edge2_C F x u y z v t: F ∔ [x, u, y] ∔ [z, v, t] ≃2 F ∔ [z, v, t] ∔ [x, u, y].
proof: Proof. Iso2 (add_edge_C _ _ _). Defined.
imports: HB(structures) Coq(Setoid Morphisms) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij equiv) GraphTheory(setoid_bigop structures pttdom mgraph ptt)