proposition: Lemma add_vlabel2_unit a x b: unit_graph2 a [tst x <- b] ≃2 unit_graph2 (a⊗b).
proof: Proof. Iso2 (add_vlabel_unit _ _). Defined.
imports: HB(structures) Coq(Setoid Morphisms) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij equiv) GraphTheory(setoid_bigop structures pttdom mgraph ptt)