proposition: Lemma add_vlabel2_two a b (x: unit+unit) c: two_graph2 a b [tst x <- c] ≃2 two_graph2 (if x then a⊗c else a) (if x then b else b⊗c).
proof: Proof. Iso2 (add_vlabel_two _ _ _ _); by case x; case. Defined.
imports: HB(structures) Coq(Setoid Morphisms) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij equiv) GraphTheory(setoid_bigop structures pttdom mgraph ptt)