proposition: Lemma par2C (F G: graph2): F ∥ G ≃2 G ∥ F.
proof: Proof. irewrite (merge_iso2 (union_C F G)) =>/=. apply merge_same. apply eqv_clot_eq; leqv. eqv. eqv. Qed.
imports: HB(structures) Coq(Setoid Morphisms) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij equiv) GraphTheory(setoid_bigop structures pttdom mgraph ptt)