proposition: Lemma relabel_unit a: relabel (unit_graph a) ≃ unit_graph (fv a).
proof: Proof. Iso bij_id bij_id xpred0. by split. Defined.
imports: HB(structures) Coq(Setoid Morphisms) mathcomp(all_ssreflect) GraphTheory(edone finite_quotient preliminaries bij equiv) GraphTheory(setoid_bigop structures pttdom mgraph ptt)