proposition: Lemma add_edge2_vlabel F x a y u z: F [tst x <- a] ∔ [y, u, z] ≃2 F ∔ [y, u, z] [tst x <- a].
proof: Proof. Iso2 (add_edge_vlabel _ _ _). Defined.
imports: HB(structures) Coq(Setoid Morphisms) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij equiv) GraphTheory(setoid_bigop structures pttdom mgraph ptt)